2020美赛E题

1.2013 MCM A: The Ultimate Brownie Pan2013 MCM B: Water, Water, Everywhere2013 ICM: Network Modeling of Earth's Health2. 2012 MCM A: The Leaves of a Tree2012 MCM B: Camping along the Big Long River2012 ICM: Modeling for Crime Busting3. 2011 MCM A: Snowboard Course2011 MCM B: Repeater Coordination2011 ICM: How environmentally and economically sound are electric vehicles? Is their widespread use feasible and practical4. 2010 MCM A: The Sweet Spot2010 MCM A: The Sweet Spot2010 ICM: The Great Pacific Ocean Garbage Patch5. 2009 MCM A: Designing a Traffic Circle2009 MCM B: Energy and the Cell Phone2009 ICM: Creating Food Systems: Re-Balancing Human-Influenced Ecosystems6. 2008 MCM A: Take a Bath2008 MCM B: Creating Sudoku Puzzles2008 ICM: Finding the Good in Health Care Systems7. 2007 MCM A: Gerrymandering2007 MCM B: The Airplane Seating Problem2007 ICM: Organ Transplant: The Kidney Exchange Problem8. 2006 MCM A: Positioning and Moving Sprinkler Systems for Irrigation2006 MCM B: Wheel Chair Access at Airports2006 ICM: Trade-offs in the fight against HIV/AIDS9. 2005 MCM A: Flood Planning2005 MCM B: Tollbooths2005 ICM: Nonrenewable Resources10. 2004 MCM A: Are Fingerprints Unique?2004 MCM B: A Faster QuickPass System2004 ICM: To Be Secure or Not to Be?11. 2003 MCM A: The Stunt Person2003 MCM B: Gamma Knife Treatment Planning2003 ICM: Aviation Baggage Screening Strategies: To Screen or Not to Screen, that is the Question12. 2002 MCM A: Wind and Waterspray2002 MCM B: Airline Overbooking2002 ICM: Scrub Lizards13. 2001 MCM A: Choosing a Bicycle Wheel2001 MCM B: Escaping a Hurricane's Wrath (An III Wind...)14. 2000 MCM A: Air Traffic Control2000 MCM B: Radio Channel Assignments2000 ICM: Elephants: When is Enough, Enough?15. 1999 MCM A: Deep Impact1999 MCM B: Unlawful Assembly1999 ICM: Ground Pollution16. 1998 MCM A: MRI Scanners1998 MCM B: Grade Inflation17. 1997 MCM A: The Velociraptor Problem1997 MCM B: Mix Well for Fruitful Discussions 18. 1996 MCM A: Submarine Tracking1996 MCM B: Paper Judging19. 1995 MCM A: Helix Construction1995 MCM B: Faculty Compensation20. 1994 MCM A: Concrete Slab Floors1994 MCM B: Network Design21. 1993 MCM A: Optimal Composting1993 MCM B: Coal-Tipple Operations22. 1992 MCM A: Air-Traffic-Control Radar Power1992 MCM B: Emergency Power Restoration23. 1991 MCM A: Water Tank Flow1991 MCM B: The Steiner Tree Problem24. 1990 MCM A: The Brain-Drug Problem1990 MCM B: Snowplow Routing25. 1989 MCM A: The Midge Classification Problem1989 MCM B: Aircraft Queueing26. 1988 MCM A: The Drug Runner Problem1988 MCM B: Packing Railroad Flatcars27. 1987 MCM A: The Salt Storage Problem1987 MCM B: Parking Lot Design28. 1986 MCM A: Hydrographic Data1986 MCM B: Emergency-Facilities Location29. 1985 MCM A: Animal Populations1985 MCM B: Strategic Reserve Management。

年份题号短名名称题型学科2014A直行与超车评价靠右行驶的政策是否正确评价类交通B大学教练评价问题设计类研究数据网络C社交网络的影响力评价研究者想在浩如烟海的信息中提取有2013A烤盘问题B水资源问题C地球健康网络建模2012A树叶问题叶子形状与树形、叶子总质量的问题设计类植物学= = B野营规划河流的trip设计、最大载客量计算规划类集合中元素的排设计类网络C犯罪克星罪犯网络，通过已知信息网络来分析2011A滑雪滑道设计如何使垂直距离最大，在空气中的扭设计类物理学设计类无线电B通讯频道问题为了防止两个频谱之间的干扰，可以C电动汽车前景问题2010A棒球棒最佳击球点问题B犯罪学(连环谋杀案搜索)问题C大太平洋塑料垃圾带2009A环岛交通管理B能源和手机C创建食物系统——重建受到人类影响的生态系统2008A球温度的上升而导致的北极冰盖的融化对陆地的影响B研制构成不同难度的数独智力游戏的算法C医保系统评价2007A不公正的选区划分B飞机就座问题C器官移植：肾交换问题2006A喷灌系统管理与移动问题B机场轮椅使用问题C抗击艾滋病的协调问题主要方法元胞自动机模拟交通流，计算评价变量网络：基于几个数据特征（中心化，连接，传递），构建相关向量，PCA阅读文献归纳总结、对阴影覆盖面积建模、自相似性、光合作用碳同化量模拟出速度、旅程中各种参数；基于队伍数量、营地数量、各种参数进行建模机器学习：基于每个节点的性质来判断是否是同谋者或leader受力分析最重要，模拟出滑道的样子并计算各种参数构建两层的网络、图论、Shannon’s information theory、naïve solution、利用Voronoi diagram构建算法用Voronoi diagram构建算法。

24美赛e题解题思路全文共四篇示例，供读者参考第一篇示例：美国大学生数学建模竞赛（MCM/ICM）是全球最具影响力的学术比赛之一，每年吸引着来自世界各地的顶尖学生参赛。

24美赛e题作为MCM/ICM比赛中的经典难题之一，一直备受关注和研究。

本文将从不同角度出发，简要介绍24美赛e题的解题思路，希望能对大家参与比赛、提高建模能力有所帮助。

我们需要了解24美赛e题的具体内容。

这道题目要求建立一个数学模型，分析对于一定间隔时间内结成的高速公路内部关键路段的平均速度。

参赛者需要考虑不同车辆的速度分布、路段长度、车辆之间的安全距离等多个因素，并提出合理的解决方案。

在解题过程中，首先需要明确题目所需研究的实际问题，确定建模的范围和目标。

然后，可以尝试构建数学模型，针对题目中提到的各种因素进行量化分析。

可以考虑利用微积分、概率统计等数学知识，结合计算机模拟和数据分析技术，分析车辆的速度分布、车流密度、路段拥堵情况等情况。

接着，可以根据建立的数学模型进行数值模拟和实验验证，调整参数、优化模型。

通过不断的尝试和实践，逐步完善模型，提高解决问题的准确性和有效性。

可以参考国内外相关领域的研究成果，借鉴其他学者的思路和方法，不断拓展思路，提高模型的创新性和实用性。

在参与24美赛e题解题时，还需要注重团队合作和沟通交流。

比赛中，每个队员可以负责不同部分的工作，共同协作完成建模和分析工作。

通过团队合作，有效分工，相互协调，密切配合，相信一定可以取得更好的成绩。

解决24美赛e题需要充分利用数学建模、数据分析和计算机技术，兼顾理论研究和实际应用，注重团队合作和创新思维。

希望大家在参加比赛时能够充分发挥自己的智慧和创造力，不断提高建模能力，获得更多的知识和经验。

祝愿大家在24美赛e题的解题过程中取得优异的成绩，为巩固和提高中国的建模实力做出贡献！第二篇示例：第24届美国数学建模竞赛（MCM）的E题是一个涉及到环境科学和气候变化的问题，要求参赛者根据提供的数据和情景，对于气候变化和海平面上升的影响进行定量分析和模拟。

马剑整理历年美国大学生数学建模赛题目录MCM85问题-A 动物群体的管理 (3)MCM85问题-B 战购物资储备的管理 (3)MCM86问题-A 水道测量数据 (4)MCM86问题-B 应急设施的位置 (4)MCM87问题-A 盐的存贮 (5)MCM87问题-B 停车场 (5)MCM88问题-A 确定毒品走私船的位置 (5)MCM88问题-B 两辆铁路平板车的装货问题 (6)MCM89问题-A 蠓的分类 (6)MCM89问题-B 飞机排队 (6)MCM90-A 药物在脑内的分布 (6)MCM90问题-B 扫雪问题 (7)MCM91问题-B 通讯网络的极小生成树 (7)MCM 91问题-A 估计水塔的水流量 (7)MCM92问题-A 空中交通控制雷达的功率问题 (7)MCM 92问题-B 应急电力修复系统的修复计划 (7)MCM93问题-A 加速餐厅剩菜堆肥的生成 (8)MCM93问题-B 倒煤台的操作方案 (8)MCM94问题-A 住宅的保温 (9)MCM 94问题-B 计算机网络的最短传输时间 (9)MCM-95问题-A 单一螺旋线 (10)MCM95题-B A1uacha Balaclava学院 (10)MCM96问题-A 噪音场中潜艇的探测 (11)MCM96问题-B 竞赛评判问题 (11)MCM97问题-A Velociraptor(疾走龙属)问题 (11)MCM97问题-B为取得富有成果的讨论怎样搭配与会成员 (12)MCM98问题-A 磁共振成像扫描仪 (12)MCM98问题-B 成绩给分的通胀 (13)MCM99问题-A 大碰撞 (13)MCM99问题-B “非法”聚会 (14)MCM2000问题-A空间交通管制 (14)MCM2000问题-B: 无线电信道分配 (14)MCM2001问题- A: 选择自行车车轮 (15)MCM2001问题-B 逃避飓风怒吼（一场恶风...） .. (15)MCM2001问题-C我们的水系-不确定的前景 (16)MCM2002问题-A风和喷水池 (16)MCM2002问题-B航空公司超员订票 (16)MCM2002问题-C (16)MCM2003问题-A: 特技演员 (18)MCM2003问题-B: Gamma刀治疗方案 (18)MCM2003问题-C航空行李的扫描对策 (19)MCM2004问题-A：指纹是独一无二的吗？ (19)MCM2004问题-B：更快的快通系统 (19)MCM2004问题-C安全与否？ (19)MCM2005问题A.水灾计划 (19)MCM2005B.Tollbooths (19)MCM2005问题C：不可再生的资源 (20)MCM2006问题A: 用于灌溉的自动洒水器的安置和移动调度 (20)MCM2006问题B: 通过机场的轮椅 (20)MCM2006问题C : 抗击艾滋病的协调 (21)MCM2007问题B ：飞机就座问题 (24)MCM2007问题C：器官移植：肾交换问题 (24)MCM2008问题A:给大陆洗个澡 (28)MCM2008问题B：建立数独拼图游戏 (28)MCM85问题-A 动物群体的管理在一个资源有限，即有限的食物、空间、水等等的环境里发现天然存在的动物群体。

2020AMC10B（美国数学竞赛）真题加详解2020 AMC 10B Solution Problem1What is the value ofSolutionWe know that when we subtract negative numbers, .The equation becomesProblem2Carl has cubes each having side length , and Kate has cubes each having side length . What is the total volume of these cubes?SolutionA cube with side length has volume , so of these will have a total volume of .A cube with side length has volume , so of these will have a total volume of .~quacker88Problem 3The ratio of to is , the ratio of to is , and the ratioof to is . What is the ratio of toSolution 1WLOG, let and .Since the ratio of to is , we can substitute in the value of toget .The ratio of to is , so .The ratio of to is then so our answeris ~quacker88Solution 2We need to somehow link all three of the ratios together. We can start by connecting the last two ratios together by multiplying the last ratio by two., and since , we can link themtogether to get .Finally, since , we can link this again to get: ,so ~quacker88Problem4The acute angles of a right triangle are and , where andboth and are prime numbers. What is the least possible value of ?SolutionSince the three angles of a triangle add up to and one of the anglesis because it's a right triangle, .The greatest prime number less than is . If ,then , which is not prime.The next greatest prime number less than is . If ,then , which IS prime, so we have our answer ~quacker88 Solution 2Looking at the answer choices, only and are coprime to . Testing , the smaller angle, makes the other angle which is prime, therefore our answerisProblem5How many distinguishable arrangements are there of 1 brown tile, 1 purple tile, 2 green tiles, and 3 yellow tiles in a row from left to right? (Tiles of the same color are indistinguishable.)SolutionLet's first find how many possibilities there would be if they were all distinguishable, then divide out the ones we overcounted.There are ways to order objects. However, since there's ways to switch the yellow tiles around without changing anything (since they're indistinguishable) and ways to order the green tiles, we have to divide out these possibilities.~quacker88SolutionWe can repeat chooses extensively to find the answer. Thereare choose ways to arrange the brown tiles which is . Then from the remaining tiles there are choose ways to arrange the red tiles. And now from the remaining two tiles and two slots we can see there are two ways to arrange the purple and brown tiles, giving us an answerofProblem6Driving along a highway, Megan noticed that her odometershowed (miles). This number is a palindrome-it reads the same forward and backward. Then hours later, the odometer displayed the next higher palindrome. What was her average speed, in miles per hour, during this -hour period?SolutionIn order to get the smallest palindrome greater than , we need to raise the middle digit. If we were to raise any of the digits after the middle, we would be forced to also raise a digit before the middle to keep it a palindrome, making it unnecessarily larger.So we raise to the next largest value, , but obviously, that's not how place value works, so we're in the s now. To keep this a palindrome, our number is now .So Megan drove miles. Since this happened over hours, she drove at mph. ~quacker88 Problem7How many positive even multiples of less than are perfect squares?SolutionAny even multiple of is a multiple of , so we need to find multiples of that are perfect squares and less than . Any solution that we want will be in theform , where is a positive integer. The smallest possible value isat , and the largest is at (where the expression equals ). Therefore, there are a total of possible numbers.-PCChess Problem8 Points and lie in a plane with . How many locations forpoint in this plane are there such that the triangle with vertices , ,and is a right triangle with area square units?Solution 1There are options here:1. is the right angle.It's clear that there are points that fit this, one that's directly to the rightof and one that's directly to the left. We don't need to find the length, we just need to know that it is possible, which it is.2. is the right angle.Using the exact same reasoning, there are also solutions for this one.3. The new point is the right angle.(Diagram temporarily removed due to asymptote error)The diagram looks something like this. We know that the altitude tobase must be since the area is . From here, we must see if there are valid triangles that satisfy the necessary requirements. First of all, because of the area.Next, from the Pythagorean Theorem.From here, we must look to see if there are valid solutions. There are multiple ways to do this:We know that the minimum value of iswhen . In this case, the equationbecomes , which is LESSthan . . The equationbecomes , which is obviously greater than . We canconclude that there are values for and in between that satisfy the Pythagorean Theorem.And since , the triangle is not isoceles, meaning we could reflectit over and/or the line perpendicular to for a total of triangles this case.Solution 2Note that line segment can either be the shorter leg, longer leg or thehypotenuse. If it is the shorter leg, there are two possible points for that cansatisfy the requirements - that being above or below . As such, thereare ways for this case. Similarly, one can find that there are also ways for point to lie if is the longer leg. If it is a hypotenuse, then thereare possible points because the arrangement of the shorter and longer legs can be switched, and can be either above or below the line segment. Therefore, the answer is .Problem9How many ordered pairs of integers satisfy theequationSolutionRearranging the terms and and completing the square for yields theresult . Then, notice that can onlybe , and because any value of that is greater than 1 will causethe term to be less than , which is impossible as must be real. Therefore, plugging in the above values for gives the ordered pairs , , , and gives a totalof ordered pairs.Solution 2Bringing all of the terms to the LHS, we see a quadraticequation in terms of . Applying the quadratic formula, weget In order for to be real, which it must be given the stipulation that we are seekingintegral answers, we know that the discriminant, must benonnegative. Therefore, Here, we see that we must split the inequality into a compound, resultingin .The only integers that satisfy this are . Plugging thesevalues back into the quadratic equation, we see that both produce a discriminant of , meaning that there is only 1 solution for . If , then the discriminant is nonzero, therefore resulting in two solutions for .Thus, the answer is .~TiblisSolution 3, x firstSet it up as a quadratic in terms of y:Then the discriminant is This will clearly only yield real solutionswhen , because it is always positive. Then . Checking each one: and are the same when raised to the 2020th power:This has only has solutions , so are solutions. Next, if :Which has 2 solutions, so andThese are the only 4 solutions, soSolution 4, y firstMove the term to the other side toget . Because for all , then . If or , the right side is and therefore . When , the right side become , therefore . Our solutions are , , , . There are solutions, so the answer is - wwt7535Problem 10A three-quarter sector of a circle of radius inches together with its interior can be rolled up to form the lateral surface area of a right circular cone by taping together along the two radii shown. What is the volume of the cone in cubicinches?SolutionNotice that when the cone is created, the radius of the circle will become the slant height of the cone and the intact circumference of the circle will become the circumference of the base of the cone.We can calculate that the intact circumference of the circle is . Since that is also equal to the circumference of the cone, the radius of the cone is . We also have that the slant height of the cone is . Therefore, we use the Pythagorean Theorem to calculate that the height of the coneis . The volume of the coneis -PCChessSolution 2 (Last Resort/Cheap)Using a ruler, measure a circle of radius 4 and cut out the circle and then the quarter missing. Then, fold it into a cone and measure the diameter to be 6cm . You can form a right triangle with sides 3, 4, and then through the Pythagorean theorem the height is found tobe . The volume of a cone is . Plugging in we findProblem11Ms. Carr asks her students to read any 5 of the 10 books on a reading list. Harold randomly selects 5 books from this list, and Betty does the same. What is the probability that there are exactly 2 books that they both select?SolutionWe don't care about which books Harold selects. We just care that Bettypicks books from Harold's list and that aren't on Harold's list.The total amount of combinations of books that Betty can selectis .There are ways for Betty to choose of the books that are on Harold's list.From the remaining books that aren't on Harold's list, thereare ways to choose of them.~quacker88Problem12The decimal representation of consists of a string of zeros after the decimal point, followed by a and then several more digits. How many zeros are in that initial string of zeros after the decimal point?Solution 1Now we do some estimation. Notice that , which meansthat is a little more than . Multiplying itwith , we get that the denominator is about . Notice that whenwe divide by an digit number, there are zeros before the first nonzero digit. This means that when we divide by the digit integer , there are zeros in the initial string after the decimal point. -PCChessSolution 2First rewrite as . Then, we know that when we write this in decimal form, there will be 40 digits after the decimal point. Therefore, we just have to findthe number of digits in .and memming (alternatively use the factthat ),digits.Our answer is .Solution 3 (Brute Force)Just as in Solution we rewrite as We thencalculate entirely by hand, first doing then multiplying that product by itself, resulting in Because this is digits,after dividing this number by fourteen times, the decimal point is beforethe Dividing the number again by twenty-six more times allows a stringof zeroes to be formed. -OreoChocolateSolution 4 (Smarter Brute Force)Just as in Solutions and we rewrite as We can then look at the number of digits in powersof . , , , , ,, and so on. We notice after a few iterations that every power of five with an exponent of , the number of digits doesn't increase. This means should have digits since thereare numbers which are from to , or digits total. This means our expression can be written as , where is in therange . Canceling gives , or zeroes before the since the number should start on where the one would be in . ~aop2014 Solution 5 (Logarithms)Problem13Andy the Ant lives on a coordinate plane and is currently at facingeast (that is, in the positive -direction). Andy moves unit and thenturns degrees left. From there, Andy moves units (north) and thenturns degrees left. He then moves units (west) and againturns degrees left. Andy continues his progress, increasing his distance each time by unit and always turning left. What is the location of the point at which Andy makes the th leftturn?Solution 1You can find that every four moves both coordinates decrease by 2. Therefore, both coordinates need to decrease by two 505 times. You subtract, giving you theanswer of ~happykeeperProblem14As shown in the figure below, six semicircles lie in the interior of a regular hexagon with side length 2 so that the diameters of the semicircles coincide with the sides of the hexagon. What is the area of the shaded region — inside the hexagon but outside all of the semicircles?Solution 1Let point A be a vertex of the regular hexagon, let point B be the midpoint of the line connecting point A and a neighboring vertex, and let point C be the second intersection of the two semicircles that pass through point A. Then, , since B is the center of the semicircle with radius 1 that C lies on, , since B is the center of the semicircle with radius 1 that A lies on,and , as a regular hexagon has angles of 120,and is half of any angle in this hexagon. Now, using the sinelaw, , so . Since the angles in a triangle sum to 180, is also 60. Therefore, is an equilateral triangle with side lengths of 1.Since the area of a regular hexagon can be found with the formula , where is the side length of the hexagon, the area of this hexagonis . Since the area of an equilateral triangle can be foundwith the formula , where is the side length of the equilateral triangle,the area of an equilateral triangle with side lengths of 1 is . Since the area of a circle can be found with the formula , the area of a sixthof a circle with radius 1 is . In each sixth of the hexagon, thereare two equilateral triangles colored white, each with an area of , and onesixth of a circle with radius 1 colored white, with an area of . The rest of the sixth is colored gray. Therefore, the total area that is colored white in each sixthof the hexagon is , which equals , and the total areacolored white is , which equals . Since the area colored gray equals the total area of the hexagon minus the area colored white,the area colored gray is , whichequals .Solution 2First, subdivide the hexagon into 24 equilateral triangles with side length1:Now note that the entire shadedregion is just 6 times this part:The entire rhombus is just 2 equilatrial triangles with side lengths of 1, so it has an area of: The arc that is not included has an area of:Hence, the area ofthe shaded region in that section is For a final areaof:Problem15Steve wrote the digits , , , , and in order repeatedly from left to right, forming a list of digits, beginning He thenerased every third digit from his list (that is, the rd, th, th, digits from the left), then erased every fourth digit from the resulting list (that is, the th, th, th, digits from the left in what remained), and then erased every fifth digit from what remained at that point. What is the sum of the three digits that were then in the positions ?Solution 1After erasing every third digit, the list becomes repeated. After erasing every fourth digit from this list, the listbecomes repeated. Finally, after erasing every fifth digit from this list, the list becomes repeated. Since this list repeats every digits andsince are respectively in we have that the th, th, and st digits are the rd, th, and thdigits respectively. It follows that the answer is~dolphin7Problem16Bela and Jenn play the following game on the closed interval of the real number line, where is a fixed integer greater than . They take turns playing, with Bela going first. At his first turn, Bela chooses any real number in theinterval . Thereafter, the player whose turn it is chooses a real numberthat is more than one unit away from all numbers previously chosen by either player. A player unable to choose such a number loses. Using optimal strategy, which player will win the game?SolutionNotice that to use the optimal strategy to win the game, Bela must select themiddle number in the range and then mirror whatever number Jennselects. Therefore, if Jenn can select a number within the range, so can Bela. Jenn will always be the first person to run out of a number to choose, so theanswer is .Solution 2 (Guessing)First of all, realize that the value of should have no effect on the strategy at all. This is because they can choose real numbers, not integers, so even if is odd, for example, they can still go halfway. Similarly, there is no reason the strategy would change when .So we are left with (A) and (B). From here it is best to try out random numbers and try to find the strategy that will let Bela win, but if you can't find it, realize thatit is more likely the answer is since Bela has the first move and thus has more control.Problem17There are people standing equally spaced around a circle. Each person knows exactly of the other people: the people standing next to her or him, as well as the person directly across the circle. How many ways are there forthe people to split up into pairs so that the members of each pair know each other?SolutionLet us use casework on the number of diagonals.Case 1: diagonals There are ways: either pairs with , pairs with , and so on or pairs with , pairs with , etc.Case 2: diagonal There are possible diagonals to draw (everyone else pairs with the person next to them.Note that there cannot be 2 diagonals.Case 3: diagonalsNote that there cannot be a case with 4 diagonals because then there would have to be 5 diagonals for the two remaining people, thus a contradiction.Case 4: diagonals There is way to do this.Thus, in total there are possible ways. Problem18An urn contains one red ball and one blue ball. A box of extra red and blue balls lie nearby. George performs the following operation four times: he draws a ball from the urn at random and then takes a ball of the same color from the box and returns those two matching balls to the urn. After the four iterations the urn contains six balls. What is the probability that the urn contains three balls of each color?SolutionLet denote that George selects a red ball and that he selects a blue one. Now, in order to get balls of each color, he needs more of both and .There are 6cases:(wecan confirm that there are only since ). However we canclump , ,and together since they are equivalent by symmetry.andLet's find the probability that he picks the balls in the order of .。

2020ICM 周末1问题E ：塑料溺水自20世纪50年代以来，塑料的制造因其多种用途而成倍增长，如食品包装、消费品、医疗器械和建筑。

虽然有很大的好处，但增加塑料生产的负面影响是令人关切的。

塑料产品不容易分解，很难处理，只有大约9%的塑料被回收[1]，每年进入海洋的大约4-1200万吨塑料废物可以看到效果[1，2]。

塑料废物具有严重的环境后果，据预测，如果我们目前的趋势继续下去，到2050年，海洋中的塑料含量将超过鱼类[2]。

对海洋生物的影响已被研究[3]，但对人类健康的影响尚未完全理解[4]单一用途和一次性塑料产品的兴起导致了致力于制造塑料废物的整个行业。

它还表明，产品有用的时间远远短于适当减少塑料浪费所需的时间。

因此，为了解决塑料废物问题，我们需要减缓塑料生产的速度，改进我们管理塑料废物的方法。

..您的团队已被国际塑料废物管理理事会（ICM ）雇用，以解决这一不断升级的环境危机。

你必须制定一个计划，以显著减少，如果不消除，一次性使用和一次性塑料产品的浪费..∙开发一个模型，以估计单一用途或一次性塑料产品废物的最大水平，这些废物可以安全地减轻，而不会造成进一步的环境损害。

在许多因素中，您可能需要考虑这种废物的来源、当前废物问题的程度以及处理废物的资源的可用性。

∙讨论在多大程度上可以减少塑料废物，以达到环境安全水平。

这可能涉及考虑影响塑料废物水平的因素，包括但不限于单一用途或一次性塑料的来源和用途、塑料替代品的可用性、对公民生活的影响，或城市、区域、国家和大陆减少单一用途或一次性塑料的政策，以及此类政策的有效性。

这些因素可能因地区而异，因此考虑到特定区域的制约因素可能会使某些政策比其他政策更有效。

∙利用你的模型和讨论，为单一用途或一次性塑料产品的全球废物的最低可达到水平设定一个目标，并讨论实现这一水平的影响。

你可以考虑改变人类生活的方式，环境影响，或对数万亿美元塑料工业的影响。

∙虽然这是一个全球性问题，但其原因和影响在各国或各区域之间并不平等分布。

美赛金融题目美国大学生数学建模竞赛分为两种类型：MCM（Mathematical Contest In Modeling）和ICM（Interdisciplinary Contest In Modeling)两种类型竞赛采用统一标准进行，竞赛题目出来之后，参数队伍通过美赛官网进行选题，一共分为6种题型。

MCM是包括A、B、C三道题目：-- A题是指连续型（continuous），具体可以理解为是连续函数建立一类模型。

常用方法是微分方程，并多为“数值分析”领域的内容，需要熟练掌握偏微分方程以及精通将连续性方程离散化求解的编程能力。

-- B题是离散型（discrete）具体需要在编程上比较熟悉计算机的“算法与数据结构”。

-- C题是数据分析型（data insights），最好是有统计学、数理金融、量化分析相关背景的知识。

C题除了MATLAB、Python还可以是用无需编程的SPSS，也可能会用到R、STATS、SAS等统计软件。

ICM包括D、E、F三道题目：-- D题一般为运筹学或网络科学（operations research/network science），近几年网络科学是一个热门研究领域，算法、软件包括可视化的软件都很多。

-- E题是环境科学题（sustainability），大体上会集中在环境污染、资源短缺、可持续发展、生态保护等几个方面。

官方给出的六个问题的描述，对于选题有一定的提示作用，但是六道题目之间没有严格的模型划分，解答范围仍然很广，每道题所用模型、方法没有明显的界限。

因此小伙伴们在寒假先要摸清楚不同题目常用的模型算法、写作套路以及题目风格，比赛时根据自己队伍擅长的东西慎重选题。

02 近五年美赛A题特点小竞分析，在六道题目中，相对而言，A题是对同学们的数学模型素养以及建模能力要求较高的。

同时A题的专业性较强，非专业相关的同学对题目的理解较难。

例如2018年的A题：多跳HF无线电传播，这道赛题包含大量的专业名词，如电离层、最大可用频率、地面源、连续跳跃、局部介电常数等，大大增加了同学们对赛题的理解难度。

题目：探讨2020中美洲及加勒比数学奥林匹克试解答---1. 引言2020年的中美洲及加勒比数学奥林匹克试解答，是一个备受关注的事件。

在数学领域，这些试题代表着挑战和机遇。

本文将深入探讨这些试题，给您带来一场关于数学奥赛的知识盛宴。

2. 试题概述2020年中美洲及加勒比地区的数学奥林匹克试题，涵盖了代数、几何、概率等多个领域。

每道题目都设计严谨，考察了考生对数学知识的深度和灵活运用能力。

试题内容不仅注重基础知识的考察，更将数学与现实生活相结合，增加了题目的趣味性和挑战性。

3. 题目解析（1）代数题在代数题部分，考生需要熟练运用代数运算、方程式求解等技巧，解决问题。

一道题目要求计算多项式的值，另一道题目则考察了对齐次方程组的解法。

这些题目旨在考察考生对代数知识的掌握情况，并培养其逻辑推理能力。

（2）几何题几何题部分则考察了考生的空间想象能力和几何推理能力。

题目设计涉及了线段、角度、多边形等几何形状，要求考生在解题过程中画出清晰准确的图形，并通过严密的证明、推理解决问题。

（3）概率题概率题部分考察了考生对概率的理解和应用能力。

题目设计涉及了随机事件、概率计算、独立事件等内容，要求考生通过分析情况、计算概率，解决实际问题。

4. 试题意义2020年中美洲及加勒比数学奥林匹克试题的设计，旨在提高学生的数学综合能力，培养他们的逻辑思维和解决问题的能力。

通过解答这些试题，考生不仅能够巩固已学的数学知识，还能够开拓思维，拓展数学视野，提高解决实际问题的能力。

5. 个人观点作为一名数学爱好者，我认为2020年中美洲及加勒比数学奥林匹克试题的设计非常有价值。

这些试题既考察了考生的数学基础知识，又注重了数学在现实生活中的应用。

通过解答这些试题，我深切感受到数学的魅力和实用性，也在实践中不断提高自己的数学素养。

6. 总结2020年中美洲及加勒比数学奥林匹克试题的内容丰富多样，题目设计严谨合理，体现了数学的广度和深度。

解答这些试题不仅有助于考生巩固数学知识，还能够培养他们的逻辑思维和问题解决能力。

2020年美赛试题全文共四篇示例，供读者参考第一篇示例：2022020年美赛试题是一个国际性的数学建模比赛，是美国大学生数学建模竞赛的简称。

该比赛每年都吸引着全球众多优秀的大学生数学爱好者参与，旨在培养学生的团队合作能力、数学建模能力和解决实际问题的能力。

2020年美赛试题包括了多个实际问题，涉及到各种不同领域的知识和技能。

有关气候变化、交通拥堵、疾病传播等方面的问题，都是参赛选手需要解决的挑战。

参赛选手需要在规定的时间内，对所选题目进行深入分析、建立数学模型、进行模拟计算，并最终给出合理有效的解决方案。

本次比赛的试题设计十分考验参赛选手的综合能力，要求他们具备较强的数学建模能力、编程能力、数据分析能力等。

参赛选手需要充分发挥团队合作精神，共同分工协作，共同完成试题，最终得出科学合理的结论。

除了在数学建模能力上的要求，参赛选手还需要具备良好的逻辑思维能力、创新能力和团队精神。

在解决实际问题的过程中，需要他们不断挑战自我，勇于探索未知领域，寻找新的解决方案。

在本次比赛中，参赛选手将会面临着各种各样的挑战和困难。

他们需要面对未知的实际问题，需要分析复杂的数据，需要精确建立数学模型，需要进行大量的模拟计算。

只有克服了这些困难，才能最终给出可信的解决方案。

2020年美赛试题的设计十分贴近实际生活，涉及到了各种领域的知识，对参赛选手提出了很高的要求。

参赛选手需要在短时间内做出合理的数学建模、给出有效的解决方案，这不仅考验了他们的数学水平，更考验了他们的团队合作能力和解决问题的能力。

通过参与这样的数学建模比赛，不仅可以提高参赛选手的综合素质，更可以锻炼他们的团队合作精神和解决问题的能力。

希望更多的大学生能够参与到类似的比赛中，不断挑战自我，不断提高自己的能力，成为未来社会的栋梁之才。

第二篇示例：2020年美国大学生数学建模竞赛（简称美赛）是一项旨在提倡学生团队合作、数学建模和创新思维的竞赛活动。

该赛事已经成为全球最具影响力的数学建模比赛之一，吸引了来自世界各地的大学生参与。

目录2018 年美赛题目翻译 (3)问题A：多跳HF 无线电传播 (3)问题B：语言传播趋势 (3)问题C ：能源配置与预测 (5)问题D：从汽油驾驶到E （电）驾驶 (6)问题E：气候变化如何影响区域不稳定？ (7)问题F：隐私成本问题 (8)2017 年美赛题目翻译 (10)问题A：管理赞比西河 (10)问题B：收费后合并 (11)问题C：“合作和导航” (12)问题D：在机场安全检查站优化乘客吞吐量 (13)问题E：规划可持续城市的发展 (15)问题F：迁移到火星：2100城市社会的乌托邦劳动力 (17)2016 年美赛题目翻译 (20)Program A 浴缸的水温模型 (20)Program B 解决空间碎片问题 (20)Program C 优质基金挑战 (21)2015 年美赛题目翻译 (21)问题一：根除病毒 (21)问题B：寻找失踪的飞机 (22)2014 年美赛题目翻译 (22)问题A：（交通流、路况）优化 (22)问题B：（体育教练）综合评价 (23)2013 年美赛题目翻译 (23)A ：平底锅受热 (23)B：可利用淡水资源的匮乏 (24)2012 年美赛题目翻译 (25)A 题：一棵树的叶子 (25)B：沿着 Big Long River 野营 (25)2011 年美赛题目翻译 (26)A:单板滑雪场地 (26)B：中继站的协调 (26)2010 年美赛题目翻译 (27)A 题：解释棒球棒上的“最佳击球点” (27)B 题系列犯罪地理效应 (27)2018年美赛题目翻译问题A：多跳HF 无线电传播背景：在高频段（HF,定义为3-10MHz），无线电波可以在地球表面和电离层之间的多次反射以进行长距离的传输（从地球表面上的一个点到地球表面上的另一个远点）。

对于低于最大可用频率（MUF）的频率，来自地面源的HF 无线电波将随着每个连续的跳跃继续前进从电离层反射回地球，在那里它们可能再次反射回到电离层，也可能再次反射回地球，等等。

2020 ICM Weekend 2Problem F: The Place I Called Home…Researchers have identified several island nations, such as The Maldives, Tuvalu, Kiribati, and The Marshall Islands, as being at risk of completely disappearing due to rising sea levels. What happens, or what should happen, to an island’s population when its nation’s land disappears? Not only do these environmentally displaced persons (EDPs) need to relocate, but there is also risk of losing a unique culture, language, and way of life. In this problem, we ask you to look more closely at this issue, in terms of both the need to relocate people and the protection of culture. There are many considerations and questions to address, to include: Where will these EDPs go? What countries will take them? Given various nations’ disproportionate contributions to the green-house gasses both historically and currently that have accelerated climate change linked to the rising seas, should the worst offenders have a higher obligation to address these issues? And, who gets a say in deciding where these nationless EDPs make a new home – the individuals, an intergovernmental organization like the United Nations (UN), or the individual governments of the states absorbing these persons? A more detailed explanation of these issues is given in the Issue Paper beginning on page 3.As a result of a recent UN ruling that opened the door to the theoretical recognition of EDPs as refugees, the I nternational C limate M igration F oundation (ICM-F) has hired you to advise the UN by developing a model and using it to analyze this multifaceted issue of when, why, and how the UN should step into a role of addressing the increasing challenge of EDPs. The ICM-F plans to brief the UN on guidance for how the UN should generate a systemized response for EDPs, especially in consideration of the desire to preserve cultural heritage. Your assignment is to develop a model (or set of models) and use your model(s) to provide the analysis to support this briefing. The ICM-F is especially interested in understanding the scope of the issue of EDPs. For example, how many people are currently at risk of becoming EDPs[1]; what is the value of the cultures of at-risk nations; how are those answers likely to change over time? Furthermore, how should the world respond with an international policy that specifically focuses on protecting the rights of persons whose nations have disappeared in the face of climate change while also aiming to preserve culture? Based on your analysis, what recommendations can you offer on this matter, and what are the implications of accepting or rejecting your recommendations?This problem is extremely complex. We understand that your submission will not be able to fully consider all of the aspects described in the Issue Paper beginning on page 3. However, considering the aspects that you address, synthesize your work into a cohesive answer to the ICM-F as they advise the UN. At a minimum, your team’s paper should include:•An analysis of the scope of the issue in terms of both the number of people at risk and the risk of loss of culture;•Proposed policies to address EDPs in terms of both human rights (being able to resettle and participate fully in life in their new home) and cultural preservation;• A description of the development of a model used to measure the potential impact of proposed policies;[1]There are multiple estimates for the current and predicted number of climate refugees in the existing literature, but they are vastly different. Therefore, you need to support your conclusions with analysis based on your own model(s), either building off of existing analysis or with a new and independent analysis.•An explanation of how your model was used to design and/or improve your proposed policies;•An explanation, backed by your analysis, of the importance of implementing your proposed policies.The ICM-F consists of interdisciplinary judges including mathematicians, climate scientists, and experts in refugee migration to review your work. Therefore, your paper should be written for a scientifically literate yet diverse audience.Your submission should consist of:•One-page Summary Sheet•Table of Contents•Your solution of no more than 20 pages, for a maximum of 22 pages with your summary and table of contents.NOTE: Reference List and any appendices do not count toward the page limit and should appear after your completed solution. You should not make use of unauthorized images and materials whose use is restricted by copyright laws. Ensure you cite the sources for your ideas and the materials used in your report.GlossaryEnvironmentally displaced persons (EDPs): people who must relocate as their homeland becomes uninhabitable due to climate change eventsCultural heritage: the ways of living of a group or society passed through generations to include customs, practices, art, and values.ICM Problem FIssue PaperAs noted in the problem statement, several island nations are at risk of completely disappearing due to rising sea levels.[1] The issue is quite complex. It is not simply a matter of identifying how to move a certain number of people around the globe – it is also about recognizing that these people are human beings who have rights and who are the last living representatives of their unique culture. In this Issue Paper, we highlight three of the essential ideas that frame this problem: relocation decisions as they relate to human rights, nation-state responsibility, and individual choice; the tension between assimilation and accommodation as part of resettlement and cultural preservation; and time factors such as the rate of the nation disappearing, the timing of these losses aligning with a global rise in nationalism, and the difficulty in making sound predictions about the size of this issue.Relocation Decisions: Human Rights, Nation-State Responsibility, and Individual Choice Considering the relocation issue, you might think that such EDPs would have similar rights as other UN-recognized refugees, but the United Nations High Commission on Refugees (UNHCR) and the widely adopted 1967 protocol has historically only afforded rights to those who are displaced due to politically related security issues, such as ethnic or religious persecution. However, in a very recent ruling, the UN has acknowledged this issue and recognized that some EDPs might qualify as refugees.[2] Although a ruling has now been made, there is not yet a vision on how the international community should respond as these situations increase in magnitude and frequency.[3]Rights awarded to these refugees include right to work, freedom of movement, and protection by host governments. Additionally, the UNHCR, in collaboration with other aid organizations, work to provide aid and assistance to refugees until they are resettled in another country, become naturalized by their host state, or repatriate to their country of origin. Now, with this new ruling, the former inhabitants of the disappeared nation may be eligible for some of those rights or aid, but there is no hope of repatriation as the land itself is gone.Even if EDPs are eligible for rights somewhere else, it is not clear where this new home would be or who would be responsible for making that decision. There are individual and international considerations related to whether the selection of a new long-term residence is made by individuals or if the choices are made or swayed by immigration policies developed by nations in isolation or as part of a cooperative effort coordinated by the United Nations. Possible migration policies could consider the financial ability of the new nation to absorb these new individuals, but there is also discussion of setting up burden-sharing based on nations’ relative contributions (pollution) to the environmental conditions that is leading to the loss of these nations. In other words, the international community may press nations with high pollution records to contribute more to the resettlement of EDPs in some equitable manner.Resettlement and Cultural Preservation: Assimilation versus AccommodationIn terms of the cultural preservation issues, the nations that are most at risk are arguably some of the most culturally distinct in the world with languages, music, art, dances, social norms, and ways of life that can be different from island to island even within the same island chain. As a result, the loss of one of these nations could represent a significant cultural loss. While the displaced inhabitants may be able to preserve some aspects of their culture, some are geographically specific. For example, traditional ocean fishing techniques used in The MarshallIslands are unlikely to continue to be practiced by families who settle in the Alps. As another example, perhaps the language could be preserved, but this would require host nations to be more accommodating and less strict on the assimilation requirements of these special new residents who may be trying to preserve their culture in a new land. For example, France current requires refugees who resettle there to learn French, but if there were international pressure, perhaps France would waive this requirement for groups of EDPs who are trying to preserve a lost culture.This leads to a tension between accommodation and assimilation as other nations volunteer to absorb the populations of the former nations. It is important to note that it is the lack of a UN protocol for dealing with EDPs that forces other nations to volunteer to settle and naturalize those affected. In fact, the loss of a nation falls into the no-man’s land between several UN charges – the care of refugees (UNHCR), the protection of world culture (United Nations Educational, Scientific, and Cultural Organization (UNESCO)), and emergency aid response (United Nations Office for the Coordination of Humanitarian Affairs (UNOCHA)). And while the residents of a handful of small island nations might be absorbed relatively easily by volunteer nations, the fact is that climate change has been ushering a literal wave of more frequent and more intense environmental disasters. Imagine a major tsunami taking out a nuclear power plant and causing enough other significant damage that a more heavily inhabited nation may become uninhabitable; or a place being hit by so many repeated severe storms that rebuilding was deemed unwise; or a place where climate change is making it impossible for a nation that was formerly flush with crops to provide for its people. At what point should the UN step in, and in what role?Time Factors: Raging Waves, Rising Seas, and Rising NationalismIf a nation is wiped out as a result of a rapid catastrophic event, such as a tsunami or hurricane, then there is no time to prepare, even if the country knew they were at risk of such an event. When a nation is sinking as a result of slowly rising sea levels, then there are issues about how a migration could be coordinated and planned, or even how the loss could be mitigated through land-preserving measures taken by the at-risk nation with or without international support. It is not clear how the timescale of the loss would impact, or should impact, the ultimate decisions that need to be made concerning the resettlement of a population, the protection of their human rights, and the preservation of their culture.Additionally, as the urgency to address this issue is literally rising with the sea level, the world is also experiencing a rise of nationalism, so the global response today may be very different than it would have been at other periods in history where globalism may have been more in favor than nationalism. If policies, or a lack of policies, end up pushing EDPs towards a subset of welcoming nations, then those countries may get overwhelmed and become less welcoming in response. Therefore, the changing global political climate may also be an important factor to consider.Lastly, all of these challenges make the size of this problem extremely difficult to predict. Credible studies have predicted anywhere from 140 million to one billion EDPs by 2050.[4,5] Summary:In summary, as a nation disappears, it is not clear if an international cooperative and coordinated effort should be adopted to address the loss of homes, the need to resettle, and the preservation of culture. This issue is complex, and no model or report would be able to adequately address everyaspect in detail, but excellent reports need to be aware of these different aspects and how they are interrelated. There is the aspect of human rights, which are now recognized in theory, but have never been applied in practice. There is the balance of individual choice versus policy-driven migration. Another aspect is defining equitable burden sharing which could be driven by the capacity for nations to absorb new residents and/or obligations due to contributions to climate change; specifically, whether the nations with the largest contributions to climate change have any ethical obligations to take on a higher burden in assisting climate refugees. Yet another aspect is a balance between assimilation and accommodation, as new residents preserve their culture and/or blend into their new home. Some nations may disappear slowly, such as sinking under rising sea levels or loss of the ability to produce food, while other nations may be wiped out in a catastrophic disaster; and the immediate needs and ability to plan for the long-term needs in these situations are different. Furthermore, the situation is evolving over time as climate change advances and as we see a global rise in nationalism. Lastly, all of this complexity has made it difficult to even measure the problem or predict how quickly it will escalate.Cited ReferencesNote that these are provided as citations to support claims in the Issue Paper. We have already pulled the important ideas from these resources for you, so although your team may use these sources, access to these is not required. Instead your team is encouraged to look for other sources to support your claims.[1]Letman, J. (2018, November 19). Rising seas give island nation a stark choice: relocate or elevate. National Geographic. Retrieved fromhttps:///environment/2018/11/rising-seas-force-marshall-islands- relocate-elevate-artificial-islands/.[2]Young, M. (2019, December 9). Climate Refugees Refused UN Protection & Denied Rights Under International Law. Retrieved from /2019/12/climate-refugees- refused-un-protection-denied-rights-international-law/.[3]Su, Y. (2020, January 29). UN ruling on climate refugees could be gamechanger for climate action. Retrieved from https:///2020/01/29/un-ruling-climate- refugees-gamechanger-climate-action/.[4]The World Bank Report. (2018, March 19). Climate Change Could Force Over 140-Million to Migration Within Countries by 2050. Retrieved fromhttps:///en/news/press-release/2018/03/19/climate-change-could-force-over- 140-million-to-migrate-within-countries-by-2050-world-bank-report.[5]Kamal, B. (2017, August 21). Climate Migrants Might Reach One Billion by 2050. Retrieved from /2017/08/climate-migrants-might-reach-one-billion-by-2050/.。

2020届上海美国学校高三英语第二次联考试卷及答案解析第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项ATop Music Festivals in 2021CoachellaSelling out fast every year, the Indio desert becomes a fashionable place where the coolest bands are watched by trendy people and celebrities. Near the top of everyone's bucket list of festivals, Coachella is a constant source of annual expectation and a hotbed for musical discussion.When &. where: April 9-11 &. 16-18, 2021; IndioUltra Music FestivalSeen as the ultimate gathering for electronic music fans across the nation and globe, the streets of Miami turn into a and bumping party with popular DJs playing what will be the sounds of summer.When & where: March 26-28, 2021; MiamiSouth By South WestRegarded as the ultimate trend-setter and launcher of careers, SXSW is an annual showcase of music, films and interactive highlights enjoyed through performances, showcases, talks, screenings and more. Virtually taking over the city of Austin, everyone in the world of music from fans to media flock here to discover the next big thing.When &, where: March 16-20, 2021; AustinThe Governors Ball Music FestivalAnother event which proves the music loving potential of Randall's Island Park is Governors Ball, an exciting and infectious mix of rock, hip-hop, electronic, pop and folk. Providing a variety of music and food tastes, whether you look to kick back and relax or dance to the beats, Governors Ball has what you want.When & where: June 11-14, 2021; New York1.Which music festival lasts the most days?A.CoachellaB.Ultra Music Festival.C.South By South WestD.The Governors Ball Music Festival.2.What is special about Ultra Music Festival?A.It's held in a park.B.It features electronic musicC.It's a gathering of popular DJs.D.It's the most popular in the country.3.Which city could you go if you love both music and movies?A.Indio.B.Miami.C.AustinD.New York.BIf you believe in thermometers (温度计), you should believe in global warming. And if you believe in eating French fries with your hamburger, you should worry more about carbonemission.It won't happen overnight, but as the planet’s climate changes, the growth cycles of main crops will all be heavily affected. Here are three of the crops that might not beat the heat.The potato actually needs a great deal of beauty rest to develop properly. “They need a cool nighttime temperature in order to start growing the tuber, the part that we eat,” Nelson says.Temperature and altitude are two primary concerns in coffee growth, and farmers are stuck between a rock and a hard place. “We know that coffee grows in a certain temperature range,” Nelson says. “They've been moving up the mountains, but at some point you run out of mountains to move up.” Higher-grade strains of Arabica coffee in Central American regions are at particular risk due to the need for lower growing temperature, especially since diseases and pests are also becoming more of a factor as temperatures rise.Even if you're looking at the direct effects of temperature alone, rice is in trouble. “As nighttime temperatures go up, the rice is going to have a problem flowering and won't make as many seeds,” Nelson says. In addition to this direct heat consequence, rising sea levels will flood many rice paddies and destroy water salinity levels, while droughts will lower production, raise prices, and further shame westerners who are clumsy with chopsticks to be able to clear their plates once a new grain is adopted.4. What is the closest meaning to the underlined word “emission” in Paragraph 1?A. Mixture.B. Pollution.C. Giving off.D. Going down.5. What does the potatoes' development need according to Nelson?A. Cool temperature at night.B. Sudden rise of the temperature.C. Enough water and salt.D. Much sunshine and fresh air.6. The rice is difficult to flower,probably because ________.A. sea levels go up suddenlyB. many seeds can't be producedC. the temperature rises at nightD. both temperature and altitude rise7. What is the best title for the text?A. How Does Global Warming Affect WesternersB. How Does the Cool Temperature Affect RiceC. What Is the Real Reason For Crops’ GrowthD. Three Crops That Won't Survive Climate ChangesCTrees are “social creature” that communicate with each other in cooperative ways that hold lessons for humans, too, ecologist Suzanne Simard says. Simard grew up in Canadian forests as a child of loggers before becoming an ecologist. She's now a professor of forest ecology at theUniversityofBritish Columbia.Trees are linked to neighboring trees by a network of fungi below the surface of the earth that resembles the nervous networks in the brain, she explains. In one study, Simard watched as a Douglas fir tree that had been injured by insects appeared to send chemical warning signals to a pine nearby. The pine tree then produced defense enzymes to protect against the insect.“This was a breakthrough,” Simard says. The trees were sharing “information that actually is important to the health of the whole forest.”In addition to warning each other of danger, Simard says that trees have been known to share nutrients at critical times to keep each other healthy. She says the trees in a forest are often linked to each other via an older tree she calls a “mother” or “hub” tree.“In connecting with all the trees of different ages, the mother trees can actually ease the growth of these young trees,” she says. “The young trees will link into the network of the old trees and benefit from that huge resource capacity. And the old trees would also pass a little bit of carbon and nutrients and water to the young trees, at crucial times in their lives, that actually help them survive.”The study of trees took on a new resonance for Simard when she suffered from breast cancer. During her treatment, she learned that one of the medicines she relied on was actually obtained from what some trees produce for their own mutual defense. She explains her research on cooperation in the forest, and shares her personal story in the new bookFinding the Mother Tree: Discovering the Wisdom of theForest.8. How could a Douglas fir tree send chemical warning signals to a pine nearby?A. By an underground network of fungi.B. By the nervous networks in the brain.C. By making cooperation with each other.D. By holding lessons to it as human beings.9. According to Simard, what was a breakthrough?A. Simard was-brought up in Canadian forests.B. She became a professor of forest ecology.C. The pine tree produced defense enzymes.D. Vital information was shared among trees.10. What helped Simard understand trees further?A. Her rich knowledge of trees.B. Her childhood in the forest.C. Her medicine gained from trees.D. Her research on cooperation.11. In Simard's book we may discover the wisdom of the forest except .A. communicating cooperativelyB. warning each other of dangerC. sharing nutrientsat critical timesD. sacrificing mother trees for survivalDThere is an old Chinese proverb that states “One generation plants the trees; another gets the shade,” and this is how it should be with mothers and daughters. The relationship between a mother and a daughter is sometimes confusing. The relationship can be similar to friendship. However, the mother and daughter relationship has unique characteristics that distinguish it from a friendship. These characteristics include responsibilities and unconditional love, whichprecludemothers and daughters from being best friends.Marina, 27 years old, said, “I love spending time with my mom, but I wouldn’t consider her my best friend. Best friends don’t pay for your wedding. Best friends don’t remind you how they carried you in their body and gave you life! Best friends don’t tell you how wise they are because they have been alive at least 20 years longer than you.” This doesn’t mean that the mother and daughter relationship can’t be very close and satisfying. This generation of mothers and adult daughters has a lot in common, which increases the likelihood of shared companionship. Mothers and daughters have always shared the common experience of being homemakers, responsible for maintaining(保持) and passing on family values and traditions. Today contemporary mothers and daughters also share the experience of work and technology, which may bring them even closer together.Best friends may ormay not continue to be best friends, but for better or worse; the mother and daughter relationship is permanent, even if for some unfortunate reason they aren’t speaking. Sometimes this is not an equal relationship. Daughters don’t always feel responsible for their mother’s emotional well-being. But mothersnever stop being mothers, which includes frequently wanting to protect their daughters and often feeling responsible for their happiness. The mother and daughter relationship is a relationship that is not replaceable by any other. Mothers always “trump(胜过)” friends.12. What does the underlined word “preclude” in paragraph 1 probably mean?A. differ.B. benefit.C. prevent.D. change.13. What can we learn from what Marina said?A. Best friends will not spend money on her wedding.B. Best friends will not remind her of important issues in life.C. Her mother is wiser on account of her age.D. Her mother is definitely not her best friend.14. Why can a mother and a daughter build a even closer relationship today?A. Because they share advanced technology with each other.B. Because they work together to support the whole family.C. Because they experience the same values and traditions.D. Because they have common experience in life and work.15. What is the text mainly about?A. How to build a good mother and daughter relationship.B. A mother-daughter relationship is irreplaceable.C. Mothers want to be daughters’ friends.D. A daughter is a mother’s best friend.第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

2020年上海美国学校高三英语第四次联考试题及答案第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项AObesity (肥胖症) is becoming a problem in our busy society, and almost one in three American adults is now considered to be obese. Children obesity is alsoat an all-time high.Obesity means being very overweight. If you are obese, you have too much bodyfat. If you eat more food than your body can use, this will make you put on weight. Food that your body does not need will be stored as fat by your body.The following are the major factors that increase the risk of obesity.What you eat plays a major role in weight gain. Eating a lot of fast food such as hamburgers, sweet drinks, ice creams and other sweet food can increase the risk of becoming obese.If you do not do enough exercise, you will put on weight as the food you eat is not being used to make energy for physical activities.The chances of you being obese are greater if your parents are obese.There are many psychological factors that cause people to eat too much. People who are worried, unhappy or bored will often eat to make themselves feel better. This is known as comfort eating.Age is another factor, as you tend (趋于) to be less active when you get older. When you get older, you need to eat less, and if you do not eat less, you will put on weight. Obesity can cause many health problems such as heart problems, high blood pressure and many other serious medical conditions.1. The underlined sentence in paragraph 1 means that ____.A. obesity does not do harm to health.B. there are more obese children than before.C. all the American children are obese.D. there are less obese children in the USA.2. According to the passage, there are ____ major factors that increase the risk of obesity.A. threeB. fourC. fiveD. six3. What will the writer most probably talk about after the last paragraph?A. How to avoid obesity.B. How to live in the busy USA.C. What illnesses are caused by obesity.D. How doctors treat heart problems.BThere are three of us in the laboratory: Jules, me and Dr. Leonards. Leonards asks me to sit in front of Jules. As I do, he looks me in the eye and starts to move his face through a series of emotions-happy, confused, surprised, glaring. I'm attracted by his display, feeling delight when hegrinsand feeling serious when his eyes narrow angrily. None of this would be a surprise, of course, if Jules were a human. But he's a robot head on a table.The most special thing is that, consciously(有意识地), there's no mistaking Jules for a real person. Although he has surprisingly realistic skin, his eyes don't fit firmly against his lids, and he has a terrible hairpiece. Yet, as I walk into the room, I experience a complex worry of feeling in his direction. It's not at all like entering an empty space. It's a bit awkward for Jules’ shining false hair. Some unconscious part of me is responding to him as if he's real. This matters, because if we're to one day live comfortably along with robots , an understanding of how we instinctively(本能地) react to them is significant. The study of these issues is the frontier of a new scientific research; human-robot interaction.Jules was built as part of an attempt to understand the emotions that can be communicated by a human. “All the robots we'vebuilt so far don't have that rich emotions. We wanted to build a robotic face, with small motors that mimic(模仿) all the muscles you have, so we could discover what it could express. "Such research is becoming increasingly important, says Dr. Leonards, partly because our rapidly ageing population will soon need the help of robots with which they can effortlessly interact.4. What does the author think of Jules?A. He ignored him in his place.B. He didn't treat him as only a robot.C. He was afraid of his being there.D. He mistook him for a real person.5. What is the purpose to build such a robot?A. To help humans of old ages.B. To carry out a scientific research.C. To take the place of human labour.D. To make an interaction with human.6. What doesthe underlined word “grins” mean in Paragraph1?A. Smiles.B. Shakes.C. Worries.D. Cries.7. What may be the best title for the text?A. Human And RobotB. Success Of Making A RobotC. Robot Will Replace ManD. Difference Between Man And RobotCThe British poet Matthew Byrne moved to Beijing in 2013 and felt that the capital city's poetry scene was lacking．His obsession（痴迷）for starting poetryevents led to the foundation of the Spittoon Collective in May 2015．“At that time，the literary activity in Beijing was The Bookworm based in Sanlitun，”Byrne says．While some of Beijing's literary institutions would go on to close in the fall of 2019，Spittoon would continue to grow as a community for poets and writers，as well as musicians and others in the creative scene．Byrne describes the Spittoon Collective as a platform for people to share ideas，from literary works to different forms of art，with projects developing from the creative energy within the community．Spittoon originally started as a poetry night at the Mado Bar in Dongcheng District 's Baochao Hutong．Byrne says，“In Beijing，you have these wonderful hutongs，ancient structures where you can walk down and visit cool bars，so I thought it would be good to have a poetry event as it seemed like poetry belonged naturally to this area．”He adds，“The objective now is to discover Chinese voices and broadcast them to the rest of the world．We create a kindof theme park-like atmosphere where every Thursday is occupied by a different literary style or art form．”The readings would mainly be in English，but with an international community，a new section called“Poetry-in-Translation”was started，which featured works in Chinese，French，Arabic，Russian，Spanish and other languages．Joining organized activities like Spittoon can be a major help for those caught up in a boring life．And it's especially important for the people who have moved to China as they need to buildnew relationships while living in a different country．8. What can we know about the Spittoon Collective?A. It was closed in 2019．B. It was set up in 2013 in Beijing．C. It's popular with literature lovers．D. It's a community just for foreigners．9. Why did Byrne start the Spittoon Collective in Baochao Hutong?A. To attract students' love of poetry．B. To expandChina's literature globally．C. To makeBeijing's hutongs famous．D. To combine poetry with the hutong．10. What effect would the Spittoon Collective have on Chinese culture?A. Beneficial．B. Negative．C. Challenging．D. Controversial．11. What is the author's attitude to the Spittoon Collective?A. Unclear．B. Intolerant．C. Doubtful．D. Favorable．DWe are in lack of enough sleep, according to Arianna Huffington, the co-founder and editor-in-chief of The Huffington Post. And thishas great consequences on our health, our job performance, our relationships and our happiness. What is needed, she ly declares, is nothing short of a sleep revolution. Only by renewing our relationship with sleep can we take back control of our lives.In her bestseller Thrive, Arianna wrote about our need to redefine success through wellbeing, wisdom, wonder, and giving. Her discussion of the importance of sleep as a gateway to this more fulfilling way of living struck such a powerful chord (弦) that she realized the mystery and transformative power of sleep called for a fuller investigation (调查).The result is a scientifically sweeping and personal exploration of sleep from all angles, from the history of sleep, to the role of dreams in our lives, to the consequences of sleep deprivation (剥夺), and the new golden age of sleep science that is showing the vital role sleep plays in our every waking moment and every aspect of our health — from weight gain, diabetes, and heart disease to cancer and Alzheimer’s.In The Sleep Revolution, Arianna shows how our cultural removal of sleep as time wasted damages our health and our decision-making and our work lives and shortens our personal lives. She explores all the latest science on what exactly is going on while we sleep and dream. She decides the dangerous sleeping pill industry, and all the ways of our addiction to technology disturb our sleep. She also offers a range of recommendations and tips from leading scientists on how we can get better and more restorative sleep.In today’s fast-paced, always-connected and sleep-deprived world, our need for a good night’s sleep is more important than ever. The Sleep Revolution both sounds the alarm on our worldwide sleep crisis and provides a detailed road map to the great sleep awakening that can help transform our lives, our communities, and our world.12. What is the first paragraph mainly about?A. The importance of sleep.B. The necessity of improving sleep.C. The way to improve our sleep.D. The effect of sleep on health.13. What can be inferred about Arianna’s attitude to success?A. She thinks good sleep is more important.B. She doesn’t think much of becoming successful.C. She thinks it wrong to sacrifice health to success.D. She is concerned about the nature of success.14. What can be said about Arianna’s investigation?A. It is really of great value.B. It is scientific and historical.C. It costs Arianna’s sleep in practice.D. It covers all necessary aspects scientifically,15. What influence does TheSleep Revolution have on society?A. It helps to slow down the pace of modern life.B. It warns people against taking sleeping pills.C. It warns the harm of inadequate sleep of people.D. It helps to stress the value of sleep to success.第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

2020届上海美国学校高三英语第四次联考试卷及参考答案第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项AGetting your kid to bed at night is seriously one of the most challenging things you'll ever have to do. Most kids are just so full of energy that they'll tire you out before they're halfway through their store of energy. An easy thing to calm down your child to get into bed is giving in and allowing some iPad screen time. However, it's really not a great idea, just like you thought.Researchers at theArizonaStateUniversityconducted a study with 547 kids between the ages of 7 to 9. Their parents tracked how much screen time the kids were allowed along with their sleep patterns. The study found that kids who did not engage in screen time before bed slept for 23 more minutes every week and also went to sleep about 34 minutes earlier than those playing with iPad. Although that might not seem like so much more time, quality of sleep is vastly important in Children's development.The CDC's (美国疾病控制中心)2018 National Youth Risk Survey outlines that good quality sleep can impact a child's life in many ways, including affecting grades and also weight gain. Students with an "A" average slept for 30 or more minutes per night than those with a "D" or"F" average.A 2018PennsylvaniaStateUniversitystudy showed that children with irregular bedtimes had a higher risk of having increased body weight. Those with consistent and age-appropriate bedtimes when they were 9 years old had a healthier BMI (体质指数)at age 15 than those with irregular bedtimes.Hard as it is, it's really important not to give in and hand over an iPad to your child who is about to go to bed. Just like it's important for adults to go to sleep without any distractions, it's even more important for kids.1. What do the findings of the researchers at theArizonaStateUniversitysuggest?A. More sleep is necessary for children's development.B. Enough sleep helps improve academic performances.C. Screen time before bed leads to later and less sleep.D. Children sleeping irregularly are easy to gain weight.2. What is the text mainly about?A. How is screen time affecting teenagers?B. What are negative effects of irregular bedtimes?C. When should you get your kid to bed at night?D. Why is screen time before bed a bad idea for kids?3. Who is the text intended for?A. Parents.B. Children.C. Teachers.D. Researchers.BThis past year, I've found myself returning again and again to lines of poetry by Emily Dickinson. Like many people, I've needed the curing effects of reading more than ever. As scientists and psychologists will tell you, books are good for the brain and their benefits are particularly vital now.Books expand our world, providing an escape and offering novelty, surprise and excitement. They broaden our view and help us connect with others. Books can also distract us and help reduce ourmental chatter.When we hit the “flow state" of reading where we're fully lost in a book, our brain's mode network calms down. It's a network of brain that is active and gets absorbed in thinking and worrying endlessly when we are not doing anything else.There is so much noise in the world right now and the very act of reading is kind of meditation. You disconnect from the chaos around you.You reconnect with yourself when you are reading. And there's no more noise.In 2020, the NPD Group recorded the best year of book sales since 2004. Yet even as people are buying more books,many are reporting they're having a harder time getting through them. It's difficult for your brain to focus on a book when it's constantly scanning for threats to keep you alive.Our fight-or-flight response has been consistently activated.Sometimes I picture my brain as a cartoon brain with little arms and legs, fighting with a book I am holding and screaming: “Can't you see I'm busy!” Anxiety causes our brain to produce a flood of stress,which consumes our energy and makes it harder to concentrate.Then one day in December sitting on my couch, I remembered how much I like to read"The House of Mirth" every few years around the holidays. The memory inspired me to pick up the familiar book, opened it up and started reading.I just kept going.The comfort and distraction and brain-opening experience gave me peace.So return to something familiar.4. What does the underlined part “mental chatter” in Paragraph 2 mean?A. Getting lost in a book.B. Non-stop inner anxiety.C. Chatting with the author.D. Powerful network of brain.5. What do we know about reading according to the text?A. It can treat our headache.B. It can calm down the noisy people.C. It forces us to concentrate.on thinking.D. It makes us communicate with ourselves.6. Why was it difficult for people to finish reading books in 2020?A. People bought too many books.B. The books were too difficult to understand.C. People just wanted to escape from the threat.D. The life threat disturbed people's focus on books.7. Why is the author's experience mentioned in the last paragraph?A. To rid people of concern for safety.B. To present an effective reading way.C. To wake up memories of an old book.D. To recommend the book he/she reads.C“Heavy hearts, like heavy clouds in the sky, are best relieved by the letting of a little water, the French writer Antoine de Rivarol wrote. This love letter to the cleansing beauty of a good cry is a comforting thought at atime when the continuing stress of the COVID-19 has added heaviness to each of our lives.Scientifically, de Rivarol's poetic image doesn't, if you'll forgive the words used in the poem, hold water. There's limited research on crying, partly because of the difficulty of copying the behavior of real crying in a lab. But even within the previous studies, there's little evidence to suggest that crying provides a physiological cleansing of poisons in people's body.Psychologists believe the relief of a good cry connects with a different emotional process. “It seems that crying occurs just after the peak of the emotional experience, and crying is associated with this return to homeostasis: the process of maintaining a stable psychological state,” said Lauren Bylsma. He also said holding back tears can have negative physical consequences, including headaches and muscle tension. Such restriction canalso limit our experiences of joy, gratitude and other positive emotions if we avoid acknowledging our feelings.For me crying has been easier said than done during the COVID-19. Psychologists say it's normal to feel stopped up by the stresses of the past year. We should find opportunities to release and process our emotions.Watching a tear-jerking movie, having an emotional conversation with a close friend, and writing in a journal are healthy ways toelicita cry. Physical activity like light-footed walking or even dancing can also signal our bodies to release some emotional tightness. We can then open up to the flow of feelings that leave us feeling lighter and refreshed—like a clear sky after a soaking rain.8. What is the weakness of the studies ever clone on crying?A. They were clone in a laboratory setting.B. They cared little about different forms of crying.C. They were always concentrated on people's daily life.D. They showed little about the positive physical effect of crying.9. What is the function of crying according to Lauren Bylsma?A. Curing people of their diseases.B. Keeping emotionally balanced.C. Producing negative mental results.D. Expanding people's experience of joy.10. What does the underlined word “elicit” in the last paragraph mean?A. Produce.B. Postpone.C. Control.D. Repeat.11. What are people advised to do according to the text?A. Learn to hold back their tears wisely.B. Share their emotion with their colleagues.C. Have a good cry when necessary.D. Try to avoid admitting our feelings.D“They’re harming your brain.” “They’re ruining your eyes.” “They’re turning you into a violent person.” The words said publicly against video games are so common, but are these worries founded on actual science? Countless studies have offered different opinions on whether video games are bad for you. We’ve rounded up the most notable reports and studies below, so you can weigh up the evidence for yourself.In 2013,psychologist(心理学家) Simone Kuhn studied the influences of spending long hours on video games on the brains of young adults and found that several areas became bigger than before. These areas are connected with highercognitive functions(认知功能), memory formation andfinemotor(精细运动) function.Last year, psychologists said that video game players who favour violent games are more likely to be violent when offline. Dr. Mark Appelbaum of the American Psychological Association said that there was a relation between violent video game use and increases in violent behaviour.Dr. Daphne Bavelier is an expert in the field of Brain & Cognitive Sciences. Bavelier presented the audience with a colour-word test, where non-gamers are easily puzzled by the test, and those who spend long periods playing on their computers are more likely to pass the test with flying colours.“Actually, those video game players have many other advantages in terms of attention,” said Bavelier, “and one part of attention which is also improved for the better is our ability to follow the movements of objects.”“So, in a sense, when we think about the influence of video games on the brain, it’s very similar to the influence of wine on the health. There are some very poor uses of wine. There are some very poor uses of video games. But when drunk in reasonable amounts, and at the right age, wine can be very good for health,” said Bavelier.12. What can be learned from Simone Kuhn’s study？A. Video games make you happier.B. Video games make your brain grow.C. Video games play a key role in memory.D. Video games teach you how to learn fast.13. What was Dr. Mark Appelbaum’s attitude towards video games？A. He was against them.B. He was hopeful of them.C.He was in favour of them.D. He was uncertain about them.14. Which of the following may Dr. Daphne Bavelier agree with？A. Video games fix attention problems.B. Video games make kids do well in exams.C. Video games encourage violent behaviour.D. Video games help increase colour knowledge.15. Why are the uses of wine mentioned in the last paragraph？A. To remind people to avoid video games.B. To show the disadvantages of video games.C. To help people learn more about video games.D.To ask people to make good use of video games.第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

2020届上海美国学校高三英语第四次联考试题及参考答案第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项AReturns & Refund Guarantee（保证；保证书）The “Returns & Refund Guarantee” is a promise provided by sellers for every item they sell on DHgate. com. When you receive an item that was bought and paid for on our site, and you find it is not as described or isof low quality, you can contact the seller to resolve these problems. DHgate will offer additional assistance if the seller is not cooperative.Scope（范围）The following points should not be included in the “Returns & Refund Guarantee”：▲The seller didn't make any promise.▲The seller can provide evidence to prove the items are as described.▲You didn't contact the seller within the promised time.▲You have released the payment to the seller before asking DHgate for help.Sellers are able to set up the following promises：Returning items for any reasonBuyers can return items for a refund within a specific date which has been set up by sellers, such as 3 days, and 7 days from the day when the items are received. The items' receiving date is the date that is indicated on the shipping carrier's official website. Buyers should prepay any return shipping cost, which will be given back to the buyers after the seller receives the items as long as the items are returned in the same exact condition as when they were delivered.Returns or Refunds accepted if the product has quality issuesBuyers can return the items for a refund when they are not as described or possess quality issues by communicating directly with the seller. The seller is responsible for the return shipping cost.Buyers can get a refund and keep the items when the items are not as described or possess quality issues by negotiating directly with sellers.1.Who can get additional assistance from DHgate in the guarantee?A.The buyers in physical stores.B.The buyers on DHgate. com.C.The sellers on DHgate. com.D.Both the buyers and the sellers.2.Which situation is within the scope of the guarantee?A.The seller didn't make any promise.B.The buyer has paid the seller in advance.C.The buyer asked for help within the promised time.D.The seller proves that there is nothing wrong with the item.3.Which of the following is true according to the passage?A.Not all the sellers make promises.B.DHgate sometimes will pay the buyers.C.Sellers should prepay return shipping cost.D.The buyer can't keep the items after getting a refund.BElonMusk is a symbol of passion, hard work and success. A person may work hard in his life, but when hard work goes along with passion and a new idea, then something is created that astonishes the world. As the founder of big companies like PayPal, SpaceX, and Tesla Motors, Elon Musk is a guide and inspiration for the youth around the world.Elon Musk was born on June 28,1971 inPretoria,South Africa. He was the eldest of three children. His father Errol Musk, a British-born South African, was an engineer. Musk spent his childhood inSouth Africaand at the age of 9, he got his first personal computer. This got Elon interested in programming and he started to learn on his own. At the age of 12, he made his first computer game, Blaster, which earned him $500 when he sold the source code to a magazine.When he was 17, he decided to leave home and had wanted to move to theUnited Statesafter graduating from a secondary school inPretoria. However, he was unable to move to theUnited States. In 1989, Elon Musk moved toCanada, where his mother’s s lived. After obtaining Canadian citizenship, Musk went toMontreal. Due to a lack of money, he found a low-paying job. At the age of 19, he enteredQueensUniversityinKingston,Ontario, studying there for two years. Finally, in 1992, his dream came true—he moved to theUnited States.As a teenager, Musk struggled with depression. But then he realized that the most important thing was presenting himself with the right questions. The day he started doing this, everything started to get easier.Musk thought that a human being had to expand the limits of his consciousness—to ask the right questions and get answers to them; thus he asked the best question of all: what will have the greatest impact on the futureof humans? Musk found that these things were the Internet and space exploration.The life of Elon Musk is inspiring. He found success on the Internet, without much formal learning. By reading books and using his willpower and dedication, he reached a level of knowledge that is difficult to imagine. He did not give up until he achieved his dreams. Elon Musk truly stands out among other billionaires because of his leadership abilities, positive attitude, ability to know when to take risks, and belief in futuristic technologies.4. According to the passage, Elon Musk gained knowledge of computer by ________.A. teaching himselfB. learning from his fatherC. taking online coursesD. studying inQueensUniversity5. What made things easier for Elon Musk when he suffered from depression?A. Expanding knowledge by reading books.B. Asking himself the right questions.C. Achieving success on the Internet.D. Designing computer games.6. What can we learn from the passage?A. It’s never too late to learn.B. Youth means limitless possibilities.C. Where there’s a will, there’s a way.D. He who doesn’t advance falls backward.7. Which words can best describe Elon Musk according to the passage?A. Optimistic and generous.B. Ambitious and determined.C. Independent and helpful.D. Adventurous and realistic.CA world in which extinct creatures could be brought back to life came a step closer yesterday. Australian scientists have managed to extract a gene from a preserved sample of a Tasmanian tiger and make it active. Thebreakthroughhas left them dreaming that one day they will be able to recreate the animal, which died out more than 70 years ago. And if it can be done with the Tasmanian tiger, it may also be possible to resurrect (复活) creatures that have been extinct for far longer.“There used to be a time when extinction meant forever, but no more, ” said Professor Mike Archer. “We are now able to seriously challenge whether those animals that have gone for ever. What has been achieved is a very important step in bringing back those animals that are extinct. And while I think that technically it is still pretty difficult at the moment, we can now see the possibilities. I’m personally convinced that the Tasmanian tiger will be brought back to life in my lifetime.”The breakthrough came after nine years of experiments by scientists at the University of Melbourne, who extracted a gene from one of several tigers preserved in alcohol in a Melbourne museum. They removed theequivalent gene from a mouse embryo implanted the tiger gene and then watched as the mouse continued to grow normally, suggesting the tiger gene had been activated.Team leader Dr. Andrew Pask said it was the first time DNA from an extinct species had been used to “induce (引起) a functional response in another living organism”.However, the animal’s entire gene structure would have to be revived in the same way to even begin the possibility of bringing the Tasmanian tiger back from the dead.Mick Mooney, a wildlife officer ofthe Tasmanian Government, was worried that such developments could encourage people’s indifference to the protection of endangered species.“If people think that we can bring animals back to life after they’ve gone, they will start saying that there is nothing to worry about because we can fix it up later.”8. What does the underlined word “breakthrough” in the l paragraph refer to?A. Scientists have recreated new animals.B. Scientists have resurrected endangered animal.C. It has turned out that some creatures would not go extinct.D. A tiger gene has been extracted successfully and activated.9. Scientists are carrying out the experiments in order to ________.A. bring extinct animals back to lifeB. transplant the genes of tigers into other animalsC. find out what factors lead to the animals’ extinctionD. find a new way to extract animals’ DNA10. Mike Archer thinks that ________.A. scientists now have no technological difficulty reconnecting extinct animalsB. it’ll be a century or so before a Tasmanian tiger walks on the earth againC. humans have come closer in reconnecting extinct animalsD. reconnecting extinct animals is impossible11. We can learn from Mick Mooncy’s words that_________.A. he thought it unnecessary to worry about endangered animalsB. his opinion is in contrast with that of the Tasmanian GovernmentC. he thought people should be encouraged to protect endangered animalsD. he is concerned that bringing extinct animals back to life may have a negative effectDThe founder of Earth Day was Gaylord Nelson, a U.S. Senator fromWisconsin. During the late 1960s, Americans witnessed the uninvited side effects of high productivity. Factories and power plants were sending out smoke and industrial waste while Americans were using petrol for their massive(大量的) cars, making air pollution almostsynonymous withthe nation’s development.What moved Senator Nelson to action was the 1969 massive oil spill inCalifornia, the largest in theUnited Statesat that time. The spill proved to be an environmental nightmare as it had a significant effect on marine life, killing about 3,500 sea birds, as well as marine animals such as dolphins, elephant seals and sea lions, fueling public anger. Inspired by the student antiwar movement at that period of time, Nelson found it an appropriate time to direct the energy of the students towards a fight for environmental protection. He decided that it was time to educate the Americans on the need to protect the environment. Thus Earth Day was born in 1970, and public environmentalawareness took centre stage.On 22ndApril 1970, millions of Americans took to the street and thousands of students marched to appeal for a healthy, sustainable environment. There was now a new synergy(协同作用) among different groups which had previously been fighting their causes related to the environment. Their fight for environmental conservation became so overwhelming that affected businesses were forced to follow environmental standards if they wanted to continue their operations.As it became more apparent that environmental issues were not just localized ones but a global concern, the year 1990 saw Earth Day reach out to many more around the world. Earth Day 1990 helped pave the way for the 1992 United Nations Earth Summit inRio de Janeiro, bringing together many nations for a united effort towards protecting the environment.12. Which of the following can replace the underlined phrase “synonymous with” in paragraph 1?A. familiar withB. opposite toC. different fromD. equal to13. Why did Nelson found Earth Day?A. To support students’ antiwar movement.B. To draw people’s attention to the seriousness of the oil spill.C. To arouse American’s awareness of environmental conservation.D. To educate Americans to protect marine life threatened by oil spill events.14. What can be inferred from the passage?A. Businesses would like to follow environmental standards.B. Earth Day united people to fight for environmental protection.C. It was the side effects of high productivity that led Nelson to take action.D. The 1992 United Nations Earth Summit made Earth Day known to more countries.15. The passage mainly talks about_______.A. how Earth Day came into beingB. why Earth Day was so significantC. who the founder of Earth Day wasD. what Earth Day meantto the world第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

IYPT2020试题以及参考中文翻译1. Invent YourselfDesign an instrument formeasuring current using its heating effect. What are the accuracy, precisionand limits of the method?1.自己发明设计一种利用热效应测量电流的仪器。

该方法的准确度、精密度和局限性是什么？2.Inconspicuous BottlePut a lit candle behind abottle. If you blow on the bottle from the opposite side, the candle may goout, as if the bottle was not there at all. Explain the phenomenon.2.不起眼的瓶子将点燃的蜡烛放在瓶子后面。

如果你从蜡烛的对面吹瓶子，蜡烛同样可能熄灭，好像瓶子根本不在那里。

解释这个现象。

3. Swinging Sound TubeA Sound Tube is a toy,consisting of a corrugated plastic tube, that you can spin around to producesounds. Study the characteristics of the sounds produced by such toys, and howthey are affected by the relevant parameters.3. 摇摆的声管声管是一种玩具，由波纹塑料管组成，你可以旋转声管产生声音。

研究这些玩具发出的声音的特性，以及它们如何受到相关参数的影响。

4. Singing FerriteInsert a ferrite rod intoa coil fed from a signal generator. At some frequencies the rod begins toproduce a sound. Investigate the phenomenon.4.“歌神”铁氧体将铁氧体棒插入信号发生器供电的线圈中。

2021年美赛E题代码在 2021 年的美赛中，E 题所涉及的代码编写是一项具有挑战性但也充满乐趣和探索空间的任务。

首先，我们来了解一下这道题目的具体要求和背景。

E 题通常会聚焦于某个现实世界中的复杂问题，可能涉及到数据分析、模型构建、算法优化等多个方面。

题目可能会给出一系列的数据和条件，要求参赛者通过编写代码来找到解决方案或者得出有价值的结论。

对于代码的编写，第一步往往是对题目进行深入的分析和理解。

这就像是在建造一座大厦之前，需要先有清晰的蓝图。

我们要仔细研究题目中给出的各种约束条件、目标和数据特点，明确我们需要解决的核心问题是什么。

在开始编写代码之前，选择合适的编程语言和工具也是至关重要的。

不同的语言在处理不同类型的问题时可能会有不同的优势。

比如说，如果需要处理大量的数据和复杂的数学计算，Python 可能是一个不错的选择，因为它拥有丰富的库和强大的数据分析能力。

而如果对性能要求极高，可能会考虑使用 C+＋等语言。

接下来就是代码的具体实现了。

在这个过程中，逻辑的清晰性和代码的可读性是非常关键的。

我们要把复杂的问题逐步分解成一个个小的模块，每个模块负责完成一个特定的功能。

这样不仅便于我们进行代码的编写和调试，也能让其他人更容易理解我们的代码思路。

比如说，如果题目要求我们对一组数据进行排序和筛选，我们可以先编写一个函数来实现排序的功能，再编写一个函数来进行筛选。

在编写这些函数的时候，要注意参数的传递和返回值的处理，确保函数的通用性和可扩展性。

在代码的编写过程中，错误处理也是不能忽视的一个环节。

因为在实际的运行中，可能会遇到各种各样的意外情况，比如输入的数据格式不正确、内存不足等等。

我们需要通过合理的错误处理机制，让程序在遇到这些问题时能够给出清晰的提示，而不是直接崩溃。

另外，代码的优化也是提高性能的重要手段。

通过对算法的改进、数据结构的选择以及代码的精简，可以大大提高程序的运行效率。

比如，如果我们需要频繁地查找某个元素，使用哈希表可能会比遍历数组更加高效。