人教版八年级下选择题专题2

八年级下学期期末重难知识点串讲+精练专题08 单项选择专练100题1．Lucy often me my best friend. They both have long curly hair.A．thinks; of B．reminds; ofC．helps; out D．leaves; out2．—The wandering Earth (《流浪地球》) tells us a story about how people try to save the earth.—Yes. In the film humans choose to stay with the earth ________ running away from it.A．because of B．together with C．such as D．instead of3．—I think I am the shyest in my class. What should I do?—Be more active in class, ________ you can improve your ability to express yourself.A．so that B．unless C．or D．although4．—Nancy ________ us a report as soon as she ________ tomorrow.—How great! I will be there.A．gives; is arriving B．gives; will arrive C．will give; arrives D．gives; arrives5．There is no reason to keep your phone at hand during a meal ________ you have some important things. A．until B．if C．when D．unless6．I knocked at the door but ___________ answered. Maybe they went to the concert.A．nobody B．somebody C．everybody D．anybody7．We kept ________ him for a long time yesterday.A．waiting B．to wait C．waiting for D．to wait for8．Andrea Bocelli never _______ ，which makes him a successful singer.A．takes away B．gives away C．gets up D．gives up9．How kind you are! You always do what you can ________ others.A．help B．helping C．helps D．to help10．Tom ________ Mary in 2000.A．gets married to B．got married with C．gets married with D．got married to11．It’s 7:00 a.m. Bob is still sleeping. Please ______.A．wake up him B．wake him upC．get up him D．get him up12．It’s ________hot today, so you can take off your sweater, Jim.A．a kind of B．a little bit C．a bit of D．a lot of13．This pair of shoes doesn’t ________ me. Do you have a larger size?A．allow B．wear C．beat D．fit14．An old man named Yu Gong tried _________the mountains.A．moves B．moving C．to move D．moved15．The Monkey King can turn himself ________ different animals and shapes.A．in B．on C．at D．into16．Our teacher reminds us ________ to study for the English test .A．remember B．to remember C．remembering.D．remembered17．He hurt his sister________ badly ________ she had to see a doctor.A．too, that B．so , that C．either, or D．too, to18．My brother will lead you _______ to my house.A．go B．going C．to go D．went19．His first book _____ in 2008.A．went out B．got out C．tried out D．came out20．I couldn’t stop ________ after I heard the news.A．laugh B．to laugh C．laughing D．laughed21．France is ______European country, while Japan is _______Asian country.A．a; a B．an; an C．an; a D．a; an22．I couldn’t believe that they ________ in solving the problem.A．included B．got C．woke D．succeeded 23．LeBron James is one of ___________ players in the NBA．He is my hero.A．better B．the best C．worse D．the worst24．Just like humans, animals will do their best to protect their young babies when they are ________. A．in danger B．on duty C．in need D．on time 25．—Would you please go to the movie with me tonight?—Sorry, I need to prepare for the exam. ________ I know, Tom wants to see a film tonight.A．As far as B．As long as C．As soon as D．As often as26．You spend too much time on your mobile phone. You are supposed to ________ the time you spend on it. A．cut off B．cut down C．cut up D．cut in27．—We should be brave when we are ________ the face of difficulty. —I agree with you.A．with B．in C．from D．through28．As we know，China has the ________ population in the world.A．most B．more C．largest D．larger29．—Don't give up ________ to achieve your dreams. —OK.I will try my best.A．try B．trying C．to try D．tried30．—Feel free ________ me if you have any problem. —That's very kind of you.A．ask B．asks C．to ask D．asking31．—Why did you open the window? —Because I want to ________ more fresh air.A．turn down B．take up C．put up D．take in32．In order to finish the project，we'll have to work ______ hours a day.A．more two B．two more C．two another D．other two33．The house is too small for the family ______.A．live in B．living in C．to live in D．lives in34．The supermarket was the first one ________ jobs for the deaf.A．providing B．to provide C．losing D．to lose35．This morning I ________ on the ice and hurt my left knee.A．fell over B．lay down C．dressed up D．hung out36．—________ is the mountain in the village?—It’s about 2,000 meters high.A．How wide B．How old C．How long D．How high37．—Is your son ______？—No. He is asleep.A．clever B．happy C．healthy D．awake38．—When did you ______ the top of the mountain?—At 11：45 a．m.A．arrive B．reach C．get D．climb 39．Now there are many tigers ______in the forests because of protection.A．to live B．living C．live D．lived 40．He cooked healthy food for the children，______ meat，rice and vegetables. A．include B．includedC．includes D．including41．—Have you seen the movie The Lion King ________?—Yes. I’ve ________ seen it. It’s wonderful.A．already; yet B．yet; yet C．already; already D．yet; already 42．—Excuse me, Linda. I don’t know your friend. Can you her to me? —Sure, I can.A．introduce B．lead C．record D．mark 43．—Oh, dear. Would you like to eat?—No, thanks. I’m full.A．else something B．else anything C．something else D．anything else 44．The storybook ________ Lucy.Don't take it away without telling her.A．is B．belongs to C．was D．belongs with 45．Sally haven’t finished her homework. ______ she didn’t write a word at all. A．Suddenly B．HardlyC．Actually D．Truly46．I like Miss Zhao because her lessons are .A．live B．lovely C．lively D．living 47．There are ____ soccer fans in the world.A．million B．three millions C．million of D．millions of 48．People often use it ____ ships.A．build B．builds C．to build D．building 49．---Look at the blue sky! The rain _________.---Let’s go out for a walk.A．stops B．will stopC．has stopped D．had stopped50．— ______, or we’ll be late for the meeting.— It’s only half past one by my watch. We have enough time left.A．Hurry up B．Don’t worryC．Never mind D．Be quiet51．Mom，I am going to ______ my best friend to you this afternoon.A．achieve B．protect C．introduce D．visit 52．When the boy saw his mother，he ran______her.A．with B．at C．towards D．from53．If you want to be a basketball player，practicing hard is the key to ______. A．success B．silence C．treasure D．dream54．I have seen two foreign films. One is made in Canada, and _______ is made in the USA．A．another B．the other C．other D．the others55．I can’t say _______ I want to visit my grandma. I haven’t met her for a long time. A．how much B．how far C．how long D．how often 56．Kate is so funny that she often makes us _______.A．laughing B．laugh C．to laugh D．laughed 57．—Whose book is that？—________．A．It is Wang Ming B．It belongs to Wang MingC．It belongs to Wang Ming’s D．It belongs to Wang Ming’s book 58．It is her dream________a famous singer．A．to become B．becoming C．to becoming D．become59．We plan to travel around．But we haven’t decided where _______．A．go B．goingC．went D．to go60．—Where is Jim？—He________to the school library．A．went B．has been C．has gone D．goes61．—Have you ever met a group of ____ on the bus?—Yes, I have.A．Germen B．Germans C．German D．Germens 62．Before you ask someone for help, find out _________ he is the right person for your problem. A．since B．that C．whether D．unless63．Many old people like to go _________ to enjoy their holiday.A．somewhere peace B．somewhere peacefulC．anywhere peaceful D．anywhere peace 64．—Dad, about _________ of our classmates wear glasses.—Oh, that’s terrible. You all should take good care of your eyes.A．three fourth B．third forth C．third fourth D．three quarters 65．—I’ve never been to the new water park. How about you, Frank?—_________. Let’s go there together!A．Neither have I B．Me, tooC．That sounds fun D．So have I66．I watched Wangwang with a friendly white cat ten minutes ago.A．played B．to play C．plays D．play67．Anna is going on a tour of Xi’an, and she wants to _____Chinese history.A．dream of B．learn about C．look through D．pass on68．I like the TV play, because its end is ______.A．peaceful B．perfectC．progress D．performance69．Jessica's parents always encourage her __________ out her own opinions.A．speak B．speaking C．to speak D．will speak 70．Have you ever read English novels? ________.A．Yes, I did B．Yes, I have C．No, I have D．No, I don't 71．When I walked past the park, I saw some old people _________ Chinese Taiji.A．do B．doing C．did D．are doing72．I think a dog is a good pet for _________ child.A．a 6-year-old B．an 6-years-old C．a 6-year old D．a 6 years-old73．The food in the restaurant is good ______ the price is too ______.A．and; high B．but; high C．but; expensive D．because; low74．Maybe when I graduate, I’ll think about ________ an English teacher.A．become B．becoming C．became D．to become75．Mr Jack ________ China for several years.A．has been to B．has come to C．has been in D．came to76．His brother ________ for three months.A．has joined the army B．has been in the armyC．has become a soldier D．joined the army77．—______to Canada?—No，never.But I______to the US a few years ago.A．Have you been；went B．Have you gone；wentC．Did you go；have gone D．Will you go；have been78．I don't have any problems ______ my English with the help of my teacher.A．improve B．improvingC．to improve D．to improving79．The phone rang after I just fell asleep and______.A．picked me up B．picked up meC．woke me up D．woke up me80．David said the Food City was a good place______Chinese food.A．ate B．to eatC．eat D．eating81．Peter, ________ honest boy, bought ________ useful dictionary in the store yesterday.A．a; a B．an; an C．a; an D．an; a82．—How can I get any information about the 2022 Winter Olympic Games?—Why not ________ for it on the Internet?A．fight B．search C．prepare D．wait83．Our teachers have been with us for nearly three years ________ we came to junior high school. We should thank them for what they have done for us.A．until B．before C．since D．when 84．—Excuse me. Could you tell me how to get to the post office?—Look out of the window of our shop. Can you see it? It is just ________ our shop. A．opposite B．above C．below D．along85．—Will you keep these old toys?—Of course. They hold the sweetest ________ about my childhood.A．gold B．silence C．research D．memories 86．—Jack hasn’t taken his piano lessons for a long time.—He is considering ________ his piano course and spending more time on his study.A．to drop B．to throw C．dropping D．throwing87．Mr. Wang always ________ his kids ________ his friends and plays with them every weekend. A．regard; as B．regards; to C．regards; as D．regard; to88．You are too late. The film ______ since half an hour ago.A．has begun B．has been on C．began D．begins89．Jenny ,hurry up you will miss the school bus．A．so B．but C．and D．or90．Your dream will come true _______ you put your heart and soul into it.A．if B．unlessC．although D．until91．—________ have you been in Shanghai? —Since five years ago.A．How old B．How long C．How much D．How soon 92．homework, we do it every day.A．As of B．As from C．As for D．As to93．Her grandmother in 1990. She has been for 23 years.A．died; died B．dead; dead C．dying; death D．died; dead 94．Betty is often seen ____ the old man with his housework.A．help B．to helpC．helped D．helps95．Our new house is close ______ the school.A．to B．from C．at D．of 96．The ship was full of people. There was no______ for Elen.A．room B．rooms C．a room D．any room 97．Cartoons are very ________, so I am very _______ in them.A．interested, interesting B．interesting, interested C．interested, interested D．interesting, interesting98．The little girl has to spend two hours the violin every day.A．to practice playing B．practicing playingC．to practice to play D．practice playing99．It’s that you have to leave so soon.A．a surprise B．bad luck C．a shame D．a pleasure 100．— May I speak to Mr. Black?— Sorry, he ______ Hong Kong. But he ______ in a few days.A．has been to; will come B．has gone to; will comeC．has been to; came D．has gone to; came。

人教版数学八年级下学期期中测试卷二一、选择题（本大题共10 小题，每小题3 分，共30 分.在每小题给出的四个选项中，只有一项是符合题目要求的）1．（3 分）计算的结果为（）A．10 B．5 C．3 D．22．（3 分）使二次根式有意义的x 的取值范围是（）A．x≠2 B．x＞2 C．x≤2 D．x≥23．（3 分）下列计算正确的是（）A．﹣＝B．+ ＝C．3 ﹣＝2 D．2+ ＝24．（3 分）下列各组数中，以a、b、c 为边的三角形不是直角三角形的是（）A．a＝1，b＝，c＝B．a＝，b＝2，c＝C．a＝，b＝，c＝D．a＝7，b＝24，c＝255．（3 分）下列命题中，是真命题的是（）A．对角线互相平分的四边形是平行四边形B．对角线相等的四边形是矩形C.对角线互相垂直的四边形是菱形D.对角线互相垂直平分的四边形是正方形6．（3 分）如图，点A（﹣4，4），点B（﹣3，1），则AB 的长度为（）A．2B．C．2D．7．（3 分）如图，桌面上的正方体的棱长为2，B 为一条棱的中点．已知蚂蚁沿正方体的表面从A 点出发，到达B 点，则它运动的最短路程为（）A．B．4 C．D．58．（3 分）若a，b，c 为直角三角形的三边，则下列判断错误的是（）A.2a，2b，2c 能组成直角三角形B.0a，10b，10c 能组成直角三角形C．能组成直角三角形D．能组成直角三角形9．（3 分）如图，若将四根木条钉成的矩形木框变形为平行四边形ABCD 的形状，并使得其面积为原矩形面积的一半，则平行四边形ABCD 的内角∠BCD 的大小为（）A．100°B．120°C．135°D．150°10．（3 分）将一张正方形纸片按如图的步骤，通过折叠得到④，再沿虚线剪去一个角，展开平铺后得到⑤，其中FM、GN 为折痕，若正方形EFGH 与五边形MCNGF 的面积之比为4：5，则的值为（）A．B．C．D．二、填空题：（本大题共6 小题，每小题3 分，共18 分）11．（3 分）化简：+（）2＝．12．（3 分）若a＝2+，b＝2﹣，则ab 的值为．13．（3 分）若平行四边形中两个内角的度数比为1：2，则其中较小的内角为．14．（3 分）如图，在3×3 的正方形网格中，每个小正方形边长为1，点A，B，C 均为格点，以点A 为圆心，AB 长为半径作弧，交格线于点D，则CD 的长为．15．（3 分）如图，有一四边形空地ABCD，AB⊥AD，AB＝3，AD＝4，BC＝12，CD＝13，则四边形ABCD 的面积为．16．（3 分）如图，△ACB 和△ECD 都是等腰直角三角形，CA＝CB，CE＝CD，△ABC 的顶点A 在△ECD 的斜边上，若AE＝，AD＝，则AC 的长为．三、解答题：（本大题共7 小题，共72 分．解答应写出文字说明、演算步骤或证明过程）17．（8 分）计算：（I）（+ ）+（﹣）；（II）2 ×÷5 ．18．（8 分）已知x＝2﹣，求代数式（7+4 ）x2+（2+ ）x+ 的值．19．（10 分）已知四边形ABCD，∠A＝∠B＝∠C＝∠D．求证：四边形ABCD 是矩形．20．（12 分）如图，在每个小正方形的边长为1 的网格中，点A、B、C 均在格点上．（1）直接写出AC 的长为，△ABC 的面积为；（2）请在如图所示的网格中，用无刻度的直尺作出AC 边上的高BD，并保留作图痕迹；（3）求BD 的长．21．（10 分）如图，在△ABC 中，∠ACB＝90°，CD⊥AB 于D，M 是斜边的中点．（I）若BC＝1，AC＝3，求CM 的长；（II）若∠ACD＝3∠BCD，求∠MCD 的度数．22．（12 分）在△ABC 中，AB＝AC＝5．（1）若BC＝6，点M、N 在BC、AC 上，将△ABC 沿MN 折叠，使得点C 与点A 重合，求折痕MN 的长；（2）点D 在BC 的延长线上，且BC：CD＝2：3，若AD＝10，求证：△ABD 是直角三角形．23．（12 分）如图，将一个正方形纸片AOBC 放置在平面直角坐标系中，点A（0，6），B（6，0），动点E 在边AO 上，点F 在边BC 上，沿EF 折叠该纸片，使点O 的对应点M 始终落在边AC 上（点M 不与A，C 重合），点B 落在点N 处，MN 与BC 交于点P．（I）求点C 的坐标；（II）当点M 落在AC 的中点时，求点E 的坐标；（III）当点M 在边AC 上移动时，设AM＝t，求点E 的坐标（用t 表示）．人教版数学八年级下学期期中测试卷二参考答案与试题解析一、选择题（本大题共10 小题，每小题3 分，共30 分.在每小题给出的四个选项中，只有一项是符合题目要求的）1．（3 分）计算的结果为（）A．10 B．5 C．3 D．2【分析】直接利用二次根式的乘法运算法则计算得出答案．【解答】解：＝5．故选：B．2．（3 分）使二次根式有意义的x 的取值范围是（）A．x≠2 B．x＞2 C．x≤2 D．x≥2【分析】利用当二次根式有意义时，被开方式为非负数，得到有关x 的一元一次不等式，解之即可得到本题答案．【解答】解：∵二次根式有意义，∴x﹣2≥0，解得：x≥2，故选：D．3．（3 分）下列计算正确的是（）A．﹣＝B．+ ＝C．3 ﹣＝2 D．2+ ＝2【分析】先把各个二次根式化成最简二次根式再合并判断即可．【解答】解：A、，错误，不符合题意；B、，错误，不符合题意；C、，正确，符合题意；D、，错误，不符合题意；故选：C．4．（3 分）下列各组数中，以a、b、c 为边的三角形不是直角三角形的是（）A．a＝1，b＝，c＝B．a＝，b＝2，c＝C．a＝，b＝，c＝D．a＝7，b＝24，c＝25【分析】根据勾股定理的逆定理：如果三角形有两边的平方和等于第三边的平方，那么这个是直角三角形判定则可．如果有这种关系，就是直角三角形，没有这种关系，就不是直角三角形．【解答】解：A、12+（）2＝（）2，符合勾股定理的逆定理，是直角三角形，故此选项错误；B、22+（）2＝（）2，符合勾股定理的逆定理，是直角三角形，故此选项错误；C、（）2+（）2≠（）2，不符合勾股定理的逆定理，不是直角三角形，故此选项正确；D、72+242＝252，符合勾股定理的逆定理，是直角三角形，故此选项错误．故选：C．5．（3 分）下列命题中，是真命题的是（）A.对角线互相平分的四边形是平行四边形B.对角线相等的四边形是矩形C．对角线互相垂直的四边形是菱形D．对角线互相垂直平分的四边形是正方形【分析】根据特殊四边形的判定定理进行判断即可．【解答】解：A、对角线互相平分的四边形是平行四边形，正确；B、对角线相等的四边形是矩形，还可能是等腰梯形，错误；C、对角线互相垂直的四边形是菱形，还可能是梯形，错误；D、对角线互相垂直平分的四边形是菱形，错误；故选：A．6．（3 分）如图，点A（﹣4，4），点B（﹣3，1），则AB 的长度为（）A．2 B．C．2 D．【分析】根据题意，可以得到AC 和BC 的长，然后利用勾股定理，即可得到AB 的长，本题得以解决．【解答】解：作BC∥x 轴，作AC∥y 轴交BC 于点C，∵点A（﹣4，4），点B（﹣3，1），∴AC＝3，BC＝1，∵∠ACB＝90°，∴AB＝＝，故选：B．7．（3 分）如图，桌面上的正方体的棱长为2，B 为一条棱的中点．已知蚂蚁沿正方体的表面从A 点出发，到达B 点，则它运动的最短路程为（）A．B．4 C．D．5【分析】正方体侧面展开为长方形，确定蚂蚁的起点和终点，根据两点之间线段最短，根据勾股定理可求出路径长，【解答】解：如图，它运动的最短路程AB＝＝，故选：C．8．（3 分）若a，b，c 为直角三角形的三边，则下列判断错误的是（）A.2a，2b，2c 能组成直角三角形B.0a，10b，10c 能组成直角三角形C．能组成直角三角形D．能组成直角三角形【分析】根据勾股定理得出a2+b2＝c2（设 c 为最长边），再逐个判断即可．【解答】解：∴a，b，c 为直角三角形的三边，设c 为最长边，∴a2+b2＝c2，A．∵a2+b2＝c2，∴4a2+4b2＝4c2，即（2a）2+（2b）2＝（2c）2，∴以2a，2b，2c 为边能组成直角三角形，故本选项不符合题意；B．∵a2+b2＝c2，∴100a2+100b2＝100c2，即（10a）2+（10b）2＝（10c）2，∴以10a，10b，10c 为边能组成直角三角形，故本选项不符合题意；C．∵a2+b2＝c2，∴a2+ b2＝c2，即（）2+（）2＝（）2，∴以，，为边能组成直角三角形，故本选项不符合题意；D．∵（）2+（）2≠（）2，∴以，，为边不能组成直角三角形，故本选项符合题意；故选：D．9．（3 分）如图，若将四根木条钉成的矩形木框变形为平行四边形ABCD 的形状，并使得其面积为原矩形面积的一半，则平行四边形ABCD 的内角∠BCD 的大小为（）A．100°B．120°C．135°D．150°【分析】作AE⊥BC 于点E．根据面积的关系可以得到AB＝2AE，进而可得∠ABE＝30°，再根据平行四边形的性质即可求解．【解答】解：如图，作AE⊥BC 于点E．∵矩形的面积＝BC•CF＝2S＝2BC•AE，平行四边形ABCD∴CF＝2AE，∴AB＝2AE，∴∠ABE＝30°，∵AB∥CD，∴∠BCD＝180°﹣∠ABE＝150°．故选：D．10．（3 分）将一张正方形纸片按如图的步骤，通过折叠得到④，再沿虚线剪去一个角，展开平铺后得到⑤，其中FM、GN 为折痕，若正方形EFGH 与五边形MCNGF 的面积之比为4：5，则的值为（）A．B．C．D．【分析】连接HF，直线HF 与AD 交于点P，根据正方形EFGH 与五边形MCNGF 的面积之比为4：5，设正方形EFGH 与五边形MCNGF 的面积为4x2，5x2，可得GF＝2x，根据折叠可得正方形ABCD 的面积为24x2，进而求出FM，最后求得结果．【解答】解：如图，连接HF，直线HF 与AD 交于点P，∵正方形EFGH 与五边形MCNGF 的面积之比为4：5，设正方形EFGH 与五边形MCNGF 的面积为4x2，5x2，∴GF2＝4x2，∴GF＝2x，∴HF＝＝2 x，由折叠可知：正方形ABCD 的面积为：4x2+4×5x2＝24x2，∴PM2＝24x2，∴PM＝2 x，∴FM＝PH＝（PM﹣HF）＝（2 x﹣2 x）＝（﹣）x，∴＝＝．故选：A．二、填空题：（本大题共6 小题，每小题3 分，共18 分）11．（3 分）化简：+（）2＝10 ．【分析】根据二次根式的性质计算．【解答】解：原式＝5+5＝10．12．（3 分）若a＝2+，b＝2﹣，则ab 的值为 1 ．【分析】直接利用平方差公式计算得出答案．【解答】解：∵a＝2+ ，b＝2﹣，∴ab＝（2+ ）×（2﹣）＝4﹣3＝1．故答案为：1．13．（3 分）若平行四边形中两个内角的度数比为1：2，则其中较小的内角为60°．【分析】首先设平行四边形中两个内角的度数分别是x°，2x°，由平行四边形的邻角互补，即可得方程x+2x＝180，继而求得答案．【解答】解：设平行四边形中两个内角的度数分别是x°，2x°，则x+2x＝180，解得：x＝60，∴其中较小的内角是：60°．故答案为：60°．14．（3 分）如图，在3×3 的正方形网格中，每个小正方形边长为1，点A，B，C 均为格点，以点A 为圆心，AB 长为半径作弧，交格线于点D，则CD 的长为3﹣．【分析】由勾股定理求出AB，再由勾股定理求出DE，即可得出CD 的长．【解答】解：连接AB，AD，如图所示：∵AD＝AB＝＝2 ，∴DE＝＝，∴CD＝3﹣．故答案为：3﹣．15．（3 分）如图，有一四边形空地 ABCD ，AB ⊥AD ，AB ＝3，AD ＝4，BC ＝12，CD ＝13，则四边形ABCD 的面积为 36 ．【分析】连接 BD ，先根据勾股定理求出 BD ，进而判断出△BCD 是直角三角形，最后用面积的和即可求出四边形 ABCD 的面积．【解答】解：如图，连接 BD ，∵在 Rt △ABD 中，AB ⊥AD ，AB ＝3，AD ＝4，根据勾股定理得，BD ＝5，在△BCD 中，BC ＝12，CD ＝13，BD ＝5，∴BC 2+BD 2＝122+52＝132＝CD 2，∴△BCD 为直角三角形，∴S 四边形 ABCD ＝S △ABD +S △BCD＝ AB •AD + BC •BD＝ ×3×4+ ×12×5＝36．故答案为：36．16．（3 分）如图，△ACB 和△ECD 都是等腰直角三角形，CA ＝CB ，CE ＝CD ，△ABC 的顶点 A 在△ ECD 的斜边上，若 AE ＝ ，AD ＝ ，则 AC 的长为 ．【分析】连接 BD ，根据等腰直角三角形性质和全等三角形的性质可得 AE ＝BD ＝，根据勾股定理可求 BC 的长，即可求解．【解答】解：如图，连接 BD ，∵△ACB 和△ECD 都是等腰直角三角形，∴CE＝CD，AC＝BC，∠ECD＝∠ACB＝90°，∠CED＝∠EDC＝45°，∴∠ACE＝∠DCB，且CE＝CD，AC＝BC，∴△ACE≌△BCD（SAS），∴AE＝BD＝，∠CED＝∠CDB＝45°，∵∠ADB＝∠EDC+∠CDB，∴∠ADB＝90°，∴AB2＝AD2+DB2＝3+7＝10，∴AB＝，∵AC2+BC2＝AB2，∴AC＝BC＝，故答案为．三、解答题：（本大题共7 小题，共72 分．解答应写出文字说明、演算步骤或证明过程）17．计算：（I）（+ ）+（﹣）；（II）2 ×÷5 ．【分析】（I）直接化简二次根式进而合并得出答案；（II）直接利用二次根式的乘除运算法则计算得出答案．【解答】解：（I）（+ ）+（﹣）＝2 +2 + ﹣＝3 + ；（II）2 ×÷5＝4 ×÷5＝3×＝．18．已知x＝2﹣，求代数式（7+4 ）x2+（2+ ）x+ 的值．【分析】首先计算x2的值，然后代入所求的式子利用平方差公式计算，最后合并同类二次根式即可．【解答】解：x2＝（2﹣）2＝7﹣4 ，则原式＝（7+4 ）（7﹣4 ）+（2+ ）（2﹣）+＝49﹣48+1+＝2+ ．19.已知四边形ABCD，∠A＝∠B＝∠C＝∠D．求证：四边形ABCD 是矩形．【分析】证出∠A＝∠B＝∠C＝∠D＝90°，直接利用三个角是直角的四边形是矩形，进而得出即可．【解答】证明：∵四边形ABCD，∠A＝∠B＝∠C＝∠D，∠A+∠B+∠C+∠D＝360°，∴∠A＝∠B＝∠C＝∠D＝90°，∴四边形ABCD 是矩形．20.如图，在每个小正方形的边长为1 的网格中，点A、B、C 均在格点上．（1）直接写出AC 的长为，△ABC 的面积为9 ；（2）请在如图所示的网格中，用无刻度的直尺作出AC 边上的高BD，并保留作图痕迹；（3）求BD 的长．【分析】（1）根据勾股定理和三角形的面积公式即可得到结论；（2）根据题意画出线段BD 即可；（3）根据三角形的面积公式即可得到结论．【解答】解：（1）AC＝＝，S△ABC＝4×5﹣×2×4﹣×2×5﹣×1×4＝9，故答案为，9；（2）如图所示，BD 即为所求，（3）∵S△ABC＝AC•BD＝BD＝9，∴BD＝．21.如图，在△ABC 中，∠ACB＝90°，CD⊥AB 于D，M 是斜边的中点．（I）若BC＝1，AC＝3，求CM 的长；（II）若∠ACD＝3∠BCD，求∠MCD 的度数．【分析】（I）先利用勾股定理求出AB，再根据直角三角形斜边上的中线等于斜边的一半的性质即可得到CM 的长；（Ⅱ）先求出∠BCD，再根据直角三角形两锐角互余求出∠B，根据直角三角形斜边上的中线等于斜边的一半可得AM＝MC，根据等边对等角可得∠ACM＝∠A，再求出∠MCD＝45°．【解答】解：（Ⅰ）∵在△ABC 中，∠ACB＝90°，BC＝1，AC＝3，∴AB＝＝，∵M 是斜边的中点，∴CM＝AB＝；（Ⅱ）∵∠ACB＝∠ACD+∠BCD＝90°，∠ACD＝3∠BCD，∴∠ACD＝90°×＝67.5°，∵CD⊥AB，∴∠A+∠ACD＝90°，∴∠A＝22.5°，∵CM＝AB＝AM，∴∠ACM＝∠A＝22.5°，∴∠MCD＝∠ACD﹣∠ACM＝67.5°﹣22.5°＝45°．22.在△ABC 中，AB＝AC＝5．（1）若BC＝6，点M、N 在BC、AC 上，将△ABC 沿MN 折叠，使得点C 与点A 重合，求折痕MN 的长；（2）点D 在BC 的延长线上，且BC：CD＝2：3，若AD＝10，求证：△ABD 是直角三角形．【分析】（1）如图1，过A 作AD⊥BC 于D，根据等腰三角形的性质得到BD＝CD＝3，求得AD ＝4，根据折叠的性质得到AM＝CM，AN＝AC＝，设AM＝CM＝x，根据勾股定理即可得到结论；（2）如图2，过A 作AE⊥BC 于E，根据等腰三角形的性质得到BE＝CE＝BC，设BC＝2t，CD ＝3t，AE＝h，得到BE＝CE＝t，根据勾股定理和勾股定理的逆定理即可得到结论．【解答】解：（1）如图1，过A 作AD⊥BC 于D，∵AB＝AC＝5，BC＝6，∴BD＝CD＝3，∴AD＝4，∵将△ABC 沿MN 折叠，使得点C 与点A 重合，∴AM＝CM，AN＝AC＝，设AM＝CM＝x，∴MD＝x﹣3，∵AD2+DM2＝AM2，∴42+（x﹣3）2＝x2，解得：x＝，∴MN＝＝＝；（2）如图2，过 A 作AE⊥BC 于E，∵AB＝AC，∴BE＝CE＝BC，∵BC：CD＝2：3，∴设BC＝2t，CD＝3t，AE＝h，∴BE＝CE＝t，∵AB＝5，AD＝10，∴h2+t2＝52，h2+（4t）2＝102，联立方程组解得，t＝（负值舍去），∴BD＝5 ，∵AB2+AD2＝52+102＝125＝（5 ）2＝BD2，∴△ABD 是直角三角形．23.如图，将一个正方形纸片AOBC 放置在平面直角坐标系中，点A（0，6），B（6，0），动点E 在边AO 上，点F 在边BC 上，沿EF 折叠该纸片，使点O 的对应点M 始终落在边AC 上（点M 不与A，C 重合），点B 落在点N 处，MN 与BC 交于点P．（I）求点C 的坐标；（II）当点M 落在AC 的中点时，求点E 的坐标；（III）当点M 在边AC 上移动时，设AM＝t，求点E 的坐标（用t 表示）．【分析】（I）根据正方形的性质可得AC⊥OA，CB⊥OB，结合A，B 两点坐标可求解；（II）根据中点的定义可得AM＝3，设OE＝x，则EM＝OE＝x，AE＝6﹣x，利用勾股定理可求解x 值，进而求解E 点坐标；（III）设点E 的坐标为（0，a），由勾股定理可求解a 值，进而求解E 点坐标．【解答】解：（I）∵正方形AOBC，A（0，6），B（6，0），∴OA＝AC＝CB＝OB＝6，且每个内角都是90°，即AC⊥OA，CB⊥OB，∴C（6，6）；（II）∵M 为AC 的中点，∴AM＝AC＝3，设OE＝x，则EM＝OE＝x，AE＝6﹣x，在Rt△AEM 中，EM2＝AM2+AE2，∴（6﹣x）2+32＝x2，解得x＝，∴E（0，）；（III）设点E 的坐标为（0，a），由题意得OE＝EM＝a，AE＝6﹣a，AM＝t，在Rt△EAM 中，EM2＝AM2+AE2，∴a2＝（6﹣a）2+t2，解得a＝，∴点E 的坐标为（0，）．。

班级 考号○ 订 ○ 内 期末素养综合测试(二)(满分100分，限时60分钟)一、选择题(每小题3分,共27分)1.(2022江西定南期中)体育活动中蕴含很多物理知识,下列相关说法中正确的是 ( )A.乒乓球被扣杀后飞向对方,说明力可以维持物体运动B.足球被踢出后仍能继续运动,是因为受到惯性力作用C.铅球落地后将地面砸了个坑,说明铅球受力发生了形变D.用力扣杀排球时手感到疼痛,说明力的作用是相互的1.答案 D 乒乓球被扣杀后飞向对方,说明力可以改变物体的运动状态,故A 错误;足球被踢出后仍能继续运动,是因为足球具有惯性,仍要保持原来的运动状态,故B 错误;铅球落地时将地面砸出了一个坑,说明力可以使物体的形状发生改变,故C 错误;用力扣杀排球时手感到疼痛,这个现象表明物体间力的作用是相互的,故D 正确。

2.【跨学科·地理】(2022河南淅川期中)如图所示,小雪用放在水平面上的两个实验装置来观察并研究大气压的变化,下列说法正确的是( )A.甲图中大气压变大时,玻璃管内的液面会上升B.乙图中大气压变小时,玻璃管内的液面会下降C.乙装置更能准确地测量出大气压的值D.两个实验装置均不受环境温度的影响2.答案 A 甲图是托里拆利实验,玻璃管内是真空,当大气压变大时,玻璃管内的液面会上升,能准确测出大气压的值;乙图中,外界大气压变小时,玻璃管内的液面会上升,瓶内封闭部分气体的压强受温度影响大,虽然能测出水柱的高度,但不知道容器内的气体压强,不能测出大气压的值。

3.在探究“杠杆平衡条件”实验中,在杠杆两侧挂上数量不等的钩码,移动钩码使杠杆在如图所示的水平位置平衡。

以下操作中,能让杠杆在水平位置再次平衡的是( )A.左、右两端,各减少一个钩码B.左、右两端的钩码下方,各增加一个钩码C.去掉左边一个钩码后把右边的平衡螺母向左调D.左边增加一个钩码且把右边的钩码向右移动一格3.答案 D 设每个钩码重力均为G ,杠杆上每小格长度为l ,A 中左端力和力臂的乘积为2G ×2l =4Gl ,右端力和力臂的乘积为G ×3l =3Gl ,两端力和力臂的乘积不相等,杠杆不平衡,不符合题意;B 中左端力和力臂的乘积为4G ×2l =8Gl ,右端力和力臂的乘积为3G ×3l =9Gl ,两端力和力臂的乘积不相等,杠杆不平衡,不符合题意;C 中去掉左边一个钩码后,探究过程中不能移动平衡螺母使杠杆平衡,不符合题意;D 中左端力和力臂的乘积为4G ×2l =8Gl ,右端力和力臂的乘积为2G ×4l =8Gl ,两端力和力臂的乘积相等,杠杆平衡,符合题意。

人教新目标英语八年级下册Unit2 I’ll help to clean the city parksSectionA一、单项选择。

( )1. Though his grandmother lives , she never feels .A. alone; aloneB. lonely; lonelyC. alone; lonelyD. lonely; alone( )2. My parents me to the zoo when I was young.A. was used to takeB. is used to takingC. used to takeD. used to taking( )3. How kind you are! You always do what you can others.A. helpB. helpsC. helpingD. to help( )4. We don’t know next. Let’s go and ask Mr. Li.A. what to doB. to do whatC. to do whichD. to do how( )5.Will you go to food at the food bank tomorrow?A. put upB. give upC. give outD. try out( ) 6.—We hope to help poor children without enough food.—You set up a food bank.A. mustB. couldC. needD. haveto( )7. My children can’t stay with me. I sometimes feel . Can you keep me company?A. excitedB. hungryC. lonelyD. tired( )8. I come here for my dictionary you borrowed from me two weeks ago.A. to askB. askC. askingD. asked( )9. —We can’t making a plan. Clean up Day is only two weeks from now.—Yes, I think so.A. put onB. put upC.put outD. put off( )10. On my way home, I saw- a granny fall down. I offered help first and then the police.A. called upB. cared forC. cheered upD. found out二、阅读理解。

Unit2练习一．选择题（共10小题）1．﹣﹣﹣I have great ______ in finishing the work by myself．Could you help me？﹣﹣﹣No problem．（）A．fun B．success C．advice D．difficulty 2．Thank you for your help，Linda．You make possible for us to finish the work in time．（）A．this B．it C．them D．that3．Last summer，I worked a volunteer for a month．It is unforgettable for me．（）A．at B．for C．with D．as4．My old neighbour Charles felt__________ after his children moved out．（）A．lonely B．safely C．angrily D．happily5．﹣﹣﹣Hi，Bruce，why do you look so tired？﹣﹣﹣I late to watch the football games last night．（）A．got up B．stayed up C．woke up D．cut up6．﹣﹣﹣What are they doing over there？﹣﹣﹣They are up some advertisements．（）A．giving B．putting C．setting D．getting7．Mary is a helpful girl．She always my pet dog while I'm away．（）A．looks for B．takes afterC．looks after D．runs after8．Please the door so that the dog can't go into the room．The babies are sleeping in the room and they are afraid of dogs．（）A．open B．close C．turn on D．turn off9．﹣﹣﹣Let's watch TV at home．﹣﹣﹣．I like it．（）A．That sounds boring B．That sounds goodC．No，it's boring D．No，I don't10．﹣﹣﹣We failed in the singing competition．﹣﹣﹣______．Better times are waiting for you．（）A．No way B．Best wishesC．Cheer up D．Good job二．填空题（共5小题）11．As a soccer player，David has to t in the playground every day．12．Can you find any（different）between the two pictures？13．A：How are you，Jane？B：Fine，（70）．And you？A：Very well．I've heard that a foreign teacher is helping the people in Ya'an．（71）don't we do something for others？B：That's a good idea．Do you have any plans for it？A：I'm going to give my old clothes to the children in the countryside together（72）my father．Would you like to join us？B：（73）love to．When shall we go there？A：I have time on （74）Friday and Saturday．How about you？B：I'm busy on Friday but （75）on Saturday morning．Shall we start at 10o'clock？A：Sorry，I'm afraid not．Let's （76）it 10：30on Saturday．B：That would be fine．Shall we meet at the school gate？A：All right．14．Helen Keller was a very bright and beautiful girl．At the age of six months，she could already say a few words．But before she was two years old，she was hit by serious illness．She could not see or hear，and soon she could not talk．When she was six，her parents invited a teacher for her．With the help of the teacher，she began to"see"and"hear"the world around her through her hands．She learned to read books for the blind people．She also learned to swim and ride a horse．After she grew up，she became a famous writer in America．Her first and most famous book is The story of my life．Her story has brought hope to many blind and deaf people．It encouraged them to live and work．根据短文内容填空，每空1词．When Helen Keller was a（66）baby，she could already say a few words．But then she was badly （67）．She could neither see nor hear and soon she could not talk．Whenshe was six，a teacher came to her．The teacher（68）her to feel the world around her through her hands．After（69）．up，she became famous as a writer．Many blind and deaf people were hopeful and encouraged to live and work（70）．of her story．15．从方框中选词并用其适当形式填空完成短文．Dear Miss Yang，I'd like to thank you for （1）money for Animal Helpers，a group that was （2）to help disabled people．You helped to make it possible for me to have"Happy"．"Happy"makesa big difference to my life．Let me （3）you my story．"Happy"is a special（4）monkey for the disabled．It is a good name for him．I （5）very happy to have him．Being unable to use my hands easily is the main （6）I face．"Happy"helps me to do many things，like opening and shutting the doors，（7）things and even answering the telephone．He （8）me up a lot．I'll send you a photo of him，and I could （9）you how he helps me too one day．I thank you again for supporting"Animal Helpers"and for （10）my life．Best wishes．Leah White．三．完形填空（共2小题）16．One day，a farmer took a bag of wheat to town．He didn't know what（1）when the bag fell off his horse．The bag was（2）heavy for him to lift．He hoped that（3）would come and help him．Before long a man came over．But the farmer was（4）when he saw the man，because he was the famous judge（法官）in"town．The farmer was afraid to ask him for（5）．As soon as he came up to the farmer，the judge（6）his horse and said，"You need my help，don't you？Let me help you．"Then he took one end of the bag，and the farmer took （7）．They（8）the bag of wheat onto the horse．"Sir，"asked the farmer，"how can I（9）you？""Well，"the judge replied，"（10）you see anyone in need of help，do the same for him．"1．A．to do B．do C．doing D．did2．A．so B．too C．such D．very3．A．anybody B．everybody C．nobody D．somebody4．A．happy B．hungry C．sad D．angry5．A．advice B．help C．money D．wheat6．A．got off B．got out C．fell off D．got on7．A．other B．another C．others D．the other8．A．dropped B．pushed C．lifted D．drew9．A．call B．pay C．stand D．afford10．A．if B．before C．until D．though．17．Years ago，while I lived in England，part of my college task（任务）was to help the children with special needs．I was chosen to（1）in a school with disabled children．The teacher asked me to（2）Nancy，a ten﹣year﹣old girl．One of（3）hands could not move．At her school the teachers would think it was an achievement（4）she was able to put on her own coat．But I saw more in her．She had always wanted to put a string（线）（5）the hole of a key．For the 5years Nancy was in the school，the teachers always（6）to help her，but always ended up doing all the work for her．I knew Nancy could do（7），so I encouraged her to do something herself．At first Nancy often failed and got very（8）Sometimes l wanted to give up too．（9），after a week Nancy was able to do（10）she had wanted to alone for so many years．Her teachers cried（11）when they saw the thing she was able to do with just some encouragement．Disabled people should（12）be told they can't do this or that．With just some encouragement they can do it．The look（13）that girl's face when she was able to do it herself meant（14）to me．I hope everyone will encourage people to do all they want by themselves（15）telling them they can't do it．1．A．read B．study C．work D．visit2．A．look after B．look for C．look at D．look over3．A．his B．her C．my D．your4．A．before B．through C．if D．until5．A．through B．across C．over D．into6．A．failed B．refused C．agreed D．tried7．A．less B．more C．nothing D．anything8．A．excited B．pleased C．unsafe D．unhappy9．A．And B．However C．But D．So10．A．which B．that C．what D．how11．A．in danger B．in fear C．with care D．with joy12．A．never B．always C．often D．sometimes13．A．of B．in C．on D．at14A．the earth B．the sun C．the moon D．the world15．A．instead of B．because C．together with D．more than．四．阅读理解（共5小题）18．Conor Grennan was unwilling to be a volunteer．The 29﹣year﹣old American was not sure if he had the skills or a strong feeling for itHowever，he went to work at an orphanage（孤儿院）in Nepal．His first thought was to make people impressed．"I thought that if I volunteered just once，I could retell the story over and over，"Grennan said in a Huffington Post articleHowever，his three﹣month stay in the orphanage turned into an unusual experience．It was in 2004and Grennan had given up his job to begin a year﹣long around﹣the﹣world trip．His first three months were spent in Nepal．When he arrived in the village，he knew nothing about the children or the local culture．When he opened the gate of the Little Princes Children's Home，he was faced by the excited children．The young American ended up caring for 18children．He later discovered that they weretrafficked（被拐卖的）children．So he walked through the mountains with great difficulty to find the kids'families．"I started walking with photos of the kids，"he told the Reuter's reporter．"I would show up in villages and show photographs around．I went with 24photos，and I found 24families．"At the same time，he put his heart into Nepalese culture．Grennan said，"V olunteering is the single best way to see how the rest of the world lives．"He also encouraged others to do what he had done．He believes that volunteering needs only making decisions to show up．Grennan's fight against child﹣trafficking has changed him．His book，Little Prince，came out last week．1．At first，Grennan simply wanted to by volunteering in Nepal．A．write travel storiesB．learn the skillsC．help the kids thereD．impress people2．When Grennan came to the Little Prince Children's Home，．A.18children were ill in bedB．the children there felt excitedC．he decided to give up his jobD．he'd lived in Nepal for a year3．From the passage we can learn that Grennan．A．found the kids'families easilyB．was good at taking picturesC．wrote the book Little PrinceD．asked others to go to Nepal4．Which is the best title for"the passage？A．V olunteering changes a lot．B．Volunteering is with the kids．C．A volunteer becomes a writer．D．A volunteer travels in Nepal．19．One day，a farmer took a bag of wheat to town．He didn't know what to do when the bag fell off his horse．The bag was too heavy for him to lift．He hoped that someone would come and help him．Before long a man came over．But the farmer's heart sank when he saw the man，because he was the famous judge（法官）in town．The farmer was afraid to ask him for help．As soon as he came up to the farmer，the judge got off his horse and said，"You need my help，don't you？Let me help you．"Then he took one end of the bag，the farmer took the other．They lifted the bag of wheat onto the horse．"Sir，"asked the farmer，"how can I pay you？""Well，"the judge replied，"if you see anyone in need of help，do the same for him．"1．The farmer did not know what to do because．A．his horse fell downB．his bag was very heavyC．he could not lift the bag himselfD．his horse ran away2．The farmer dared not ask for help．A．someoneB．the famous judgeC．one of his friendsD．the other farmer3．When he saw what had happened，the judge．A．asked the farmer to get on the horseB．helped the farmer lift the bag onto the horseC．refused to help the farmerD．got off his horse4．"If you see anyone in need of help，do the same for him．"means"If anyone．"A．helps you，do the same for himB．needs help，help himC．is in need of help，tell him the sameD．helps you，help him5．The best title of this story is""．A．A Bag of WheatB．Heavy BagC．Do the Same For HimD．The Farmer．20．Jack Brown，an office worker，lives in Washington．He inherited（继承）a million dollars when he was 23．but he wasn't happy at all．When his college friends were looking for their jobs，he didn't have to．Jack decided to live a simple life like everyone else．He gave $10，000 0f his money to a charity to help poor children live a better life．Today he is 36．He still wears cheap shoes and clothes and drives a small car only，but he is very happy．Up to now Jack has helped some children from poor countries all over the world by sending them $ 200 a month．The money was used for the children's study，food，medicine and clothing．Jack received a report each year on the children's progress．They can write to each other，but usually the children do not speak English．When Jack first heard about these children，he wanted to help them．"It was nothing special，"he said．"Unti1 I went to these countries and met the children I was helping，I didn't know anything about their life．"Once lack went to meet a little girl in Africa．He said that the meeting was very exciting．"When I met her，I felt very，very happy，"he said．"And I saw that the money was used for a good cause．It brought me happiness．I want to do everything I can to go on helping these children．"1．Why didn't Jack need to look for a job？A．Because he is an office worker．B．Because he lives in Washington．C．Because he went to college．D．Because he got one million dollars．2．How has Jack helped poor children all over the world？A．By sending them each 200amonth．B．Bygiving，10，000 0f his money to a charity．C．By writing letters and reports to them．D．By buying food，medicine and clothing for them．3．Jack learned about the children's progress byA．visiting them each yearB．asking his college friendsC．getting a report every yearD．talking with them in English4．The underlined words"for a good cause"mean""in Chinese．A．功绩B．行善C．优惠D．赏赐5．What does the writer want to tell us through the story？A，Help others and you will feel happy．B．Poor children need our help．C．Living a simple life is the secret to happiness．D．Giving your money to poor children，please．21．Are you looking for something fun and would you like to help others in your spare time？Then join us to be a volunteer!We're a non﹣profit（非盈利的）organization．We have volunteer jobs of all ages．Anyone，from twelve﹣year﹣old children to people in their seventies can become a volunteer．You can help people in many ways．Schools need help with taking care of children while parents are working．Hospitals need volunteers to look after children while their parents are seeing a doctor．Animal lovers can help take care of those dogs and cats without homes．There is something for everyone．"As a volunteer，I don't want to get anything．Seeing the children's happy faces，I'm happy，too，"said Carlos Domingo，an old woman of 62．"I often played computer games in my spare time before．Now I help older people learn how to use computers，"said another volunteer at the age of 18．If everyone helps out a bit，we'll have a better world to live in．Interested？Call us at 010﹣800﹣555﹣5756or visit our website：www．activol．com．1．can be a volunteer．A．ChildrenB．Old womenC．Anyone aged 12～70D．Young people2．Volunteers want to get when they help others．A．moneyB．computersC．everythingD．nothing3．Carlos Domingo does volunteer work with．A．animalsB．childrenC．computersD．older people4．We can probably read such a passage．A．in a newspaperB．in a storybookC．in a picture bookD．in a textbook．22．Dear Brad，In about 3months，I will take a very important test．If I（1）（pass）the test with good grades，I can get to the 10th grade and choose a good school（2）（study）in．NowI am trying my best to make my dream （3）（come）true．At the same time，I'm the monitor in my class，which means I should do lots of things for my class．I am so busy with my school work and duties as a monitor that I don't have enough time（4）（keep）a balance between them．Gradually I become lazy．The other day，my head teacher（5）（tell）me that she was disappointed in my poor performance as the class monitor．Her words really discouraged me．What should I do now，to give up or not to give up as the class monitor？I must（6）（do）my best in school because how well I do will influence where I go after this school year is over and it can affect the rest of my life．（7）（be）a class monitor is also a valuable learning experience because my teacher trusts me（8）（be）a good leader．I don't want （9）（go）to my parents for suggestions，for they will get worried about me．Can you tell me how （10）（choose）？Yours，Gates．五．句型转换（共5小题）23．Can you care for my pet while I am away？（改为同义句）Can you my pet while I am away？24．They made a decision to travel abroad．（改为同义句）They travel abroad．25．We need to think up some good ideas．（改为同义句）We need to some good ideas．26．1．欢呼；喝彩．2．义务者；志愿者3．孤独的，寂寞的4．募集；征集5．打扫干净6．（使）变得更高兴；振奋起来7．分发；散发8．想出；提出9．推迟10．打电话给（某人）；征召11．曾经…；过去…12．照顾；非常喜欢．27．1．run out of．2．put up some signs3．ask…for…4．be on the phone 5．tell sb．about sth 6．work out．Unit2练习参考答案与试题解析一．选择题（共10小题）1．【分析】﹣我自己独自完成这项工作有困难，你能帮助我吗？﹣没问题．【解答】答案：D；A．fun 乐趣；B．success 成功；C．advice 建议；D．difficulty困难．根据句中信息Could you help me推测上句句意：我自己独自完成这项工作有困难；have difficulty in doing在做某事上有困难，故选D．2．【分析】谢谢你的帮助，Linda．你使我们有可能按时完成工作．【解答】答案：B．当不定式、动名词、从句等复杂成分用作宾语且其后跟有宾语补足语时，通常会在宾语补足语前使用形式宾语it，而将真正的宾语移至句末，其基本结构为"动词+it+宾语补足语+不定式（动名词或从句）"，it 做形式宾语时，通常和下列动词连用：consider，think，make，find，feel，see，take，suppose等．故本题选it做形式宾语，真正的宾语是"to finish the work in time"，them他们（宾格），this这个（近指，单数），that那个（远指，单数），这两个都是指示代词，这三个词都没有这种用法，故选：B．3．【分析】去年暑假，我作为志愿者工作了一个月，对我来说难以忘怀．【解答】答案：D根据题意"去年暑假，我作为志愿者工作了一个月，对我来说难以忘怀"，work as以…身份而工作，这是固定用法，故选D．4．【分析】当他的孩子搬走以后，我的老邻居Charles感到很孤独．【解答】答案：A；lonely孤独的；safely安全地；angrily愤怒地；happily高兴地；根据句中信息after his children moved out推测Charles感到孤独；feel是感官动词，其后可加形容词，表示"感到"的结果；故选A．5．【分析】﹣你好，布鲁斯，你为什么看起来这么疲倦？﹣我昨天晚上看足球比赛熬夜到很晚．【解答】答案：B根据题意"你好，布鲁斯，你为什么看起来这么疲倦？﹣我昨天晚上看足球比赛熬夜到很晚"，可知熬夜看足球赛，结合选项，A．起床B．熬夜C．醒来D．切碎．故选：B．6．【分析】﹣他们在那边做什么？﹣他们正在张贴广告．【解答】答案：B根据题意"﹣他们在那边做什么？﹣他们正在张贴广告．"，可知问句是现在进行时，所以回答也用现在进行时be+doing，由up some advertisements，可知是put up张贴，故选B．7．【分析】Mary是乐于助人的女孩，当我离开的时候，她总是照顾我的宠物狗．【解答】答案：C根据题意"Mary是乐于助人的女孩，当我离开的时候，她总是照顾我的宠物狗"，可知是一般现在时；由my pet dog while I'm away推出是照顾我的狗，结合选项，A．寻找B．看起来像C．照顾D．追赶，故选C．8．【分析】请关上门，为的是不让狗进到房间里去．孩子们正在房间里睡觉而且他们害怕狗．【解答】答案：B根据句意，不让狗进到房间，所以是关上门的意思，不能用open，open是打开门的意思．而turn on打开和turn off关上，是指电器类的打开和关上．如果指关上门之类的，要用close．又因为是祈使句，故用动词原形close．故选B．9．【分析】﹣﹣让我们在家看电视．﹣﹣听起来不错，我喜欢．【解答】答案：B．That sounds boring那听起来很无聊；That sounds good听起来不错；No，it's boring不，太无聊了；No，I don't不，我没有．根据Let's watch TV at home．这里表示意见或者建议，而I like it表示喜欢，那么用That sounds good听起来不错回答．故选B．10．【分析】﹣﹣我们唱歌比赛输了．﹣﹣振作起来．更好的时机在等着你．【解答】答案：C No way决不；Best wishes最美好的祝愿、祝福；Cheer up振作起来；Good job做得好．根据We failed in the singing competition．我们唱歌比赛输了．Better times are waiting for you．更好的时机在等着你．可知下文应该是鼓励的话．应该是Cheer up，故填：C．二．填空题（共5小题）11．【分析】作为一名足球运动员，大卫每天都要在操场上训练．【解答】答案：train．考查动词．句意"作为一名足球运动员，大卫每天都要在操场上___．"，及首字母提示，可知应该是"训练"train动词．不定式to后用原形train．12．【分析】你能找出这两幅画的不同之处吗？【解答】答案：differences．根据Can you find any﹣﹣（different）between the two pictures，可知你能找出这两幅画的不同之处吗？any表示一些，通常用于一般疑问句和否定句中，后面跟名词复数形式．故填differences．13．【分析】A：你好吗，简？B：很好，谢谢，你呢？A：很好．我听说有一位外籍教师在帮助雅安人民．我们为什么不为别人做点什么呢？B：那是个好主意．你有什么计划吗？A：我要和爸爸一起把我的旧衣服送给乡下的孩子，你愿意和我们一起去吗？B：我愿意去，什么时候我们去那儿？A：星期五和星期六我都有时间，你呢？B：星期五我很忙，但星期六上午有空．我们十点可以吗？A：对不起，恐怕不行．咱们定在星期六十点半吧．B：那太好了．我们在校门口见面好吗？A：好的．【解答】70．thanks考查文章的理解和上下文的联系．根据上一句：很好，可知此处应该是：谢谢．故填thanks．71．Why考查文章的理解和上下文的联系．根据下一句：那是个好主意，可知此处应该是：我们为什么不为别人做点什么呢？故填Why．72．with考查文章的理解和上下文的联系．根据上一句：你有什么计划吗？可知此处应该是：我要和爸爸一起把我的旧衣服送给乡下的孩子．故填with．73．I'd考查文章的理解和上下文的联系．根据下一句：你愿意和我们一起去吗？可知此处应该是：我愿意去．故填I'd．74．both考查文章的理解和上下文的联系．根据题干此处是固定词组both…and两个都…，结合句意：星期五和星期六我都有时间．故填both．75．free考查文章的理解和上下文的联系．根据上一句：星期五我很忙，可知此处应该是：但星期六上午有空．故填free．76．make考查文章的理解和上下文的联系．根据下一句：那太好了，可知此处应该是：咱们定在星期六十点半吧．根据题干可知这是祈使句，动词应该用原形，故填make．14．【分析】这是一篇关于海伦•凯勒生平的文章．海伦•凯天生聪明，但是她在2岁生了一场大病后，慢慢地看不见，也听不见了，但是她并没有因此而灰心，而是学会了盲文，自己后来成了一名美国的著名的作家，她的故事激励着那些聋哑人继续生活下去．【解答】66．six﹣month﹣old．细节理解题．考查海伦•凯勒说话时的年龄．根据文中"At the age of six months，she could already say a few words"可知，在6个月大时，她已经会（断断续续）说几句话．at the age of six months在六个月大时；a six﹣month﹣old baby六个月大的婴儿．故填six﹣month﹣old．67．ill/sick．细节理解题．考查海伦•凯勒遭受什么样的打击．根据文中"But before she was two years old，she was hit by serious illness"可知，在她2岁大时，她遭受重病的打击．hit 打击．be badly ill/sick得了重病．故填形容词ill/sick．68．helped/taught．细节理解题．考查海伦•凯勒的老师的教学方法．根据"With the help of the teacher，she began to see and hear the world around her through her hands"可知，她通过老师的手感知外部世界．本题变为help/teach sb through sth句型，意思是"通过某种方式帮助（教）某人．一般过去时．故填helped/taught．69．growing．细节理解题．考查海伦•凯勒的成就．根据文中"After she grew up，she becamea famous writer in America"可知，她长大后，成为美国著名作家．上句中主从句主语相同，故可把从句改为动名词结构，并省略主语．after growing up 长大后．故填growing．70．because．细节理解题．考查海伦•凯勒的事迹的激励作用．根据文中最后两句"Her story has brought hope to many blind and deaf people．It encouraged them to live and work"可知，其事迹鼓舞着很多盲人和聋哑人工作和生活下去．because of 因为，后跟名词或代词；because of her story因为她的故事．故填because．15．【分析】文章是Leah White写给Miss Yang的一封信，信中感谢Miss Yang对"动物助手"的支持，并介绍了自己的小助手"Happy"．【解答】1．raising考查动词，根据money for Animal Helpers，可知是为Animal Helpers 募捐，结合选项，"raise筹集"符合题意，结合介词for后面接动名词，故填raising．2．set up考查短语，根据句子结构，可知a group 是定语从句的先行词，句意：小组被建立的目的是为了帮助残疾人，结合选项"set up建立"符合题意，结合语态为被动语态be+过去分词，故填set up．3．tell考查动词，根据you my story，可知讲故事用动词"tell"，结合句型let sb do sth 让某人做某事，故填tell．4．trained考查动词，根据monkey for the disabled，可知是一只帮助残疾人的猴子，所以这只猴子应该是"被训练"好的，此处是过去分词表被动，把train变成trained符合题意，故填trained．5．feel 考查动词，根据very happy，结合选项，可知是"感觉"很开心，结合时态为一般现在时，主语是我，故填feel．6．difficulty考查名词，根据Being unable to use my hands easily不能轻易地使用我的手，可知这是一种困难，此处是名词，结合选项，把"difficult"变成名词difficulty符合题意，故填difficulty．7．carrying考查动词，根据Happy"helps me to do many things，like opening and shutting the doors，可知这只猴子能做很多事情，推出此处是"拿东西"，所以"carry"符合题意，结合介词like后接动名词，故填carrying．8．cheers考查动词，根据me up，结合选项，可知是短语cheer up使…高兴，结合时态为一般现在时，主语是三单式he，所以动词用cheers，故填cheers．9．show考查动词，故据how he helps me他如何帮我的，可知是向你"展示"一下他是如何帮我的，结合选项，"show"符合题意，结合could+动词原形，故填show．10．changing 考查动词，根据my life，结合选项，可知"change改变"符合题意，句意是"改变了我的生活"，结合介词for后面接动名词，故填changing．三．完形填空（共2小题）16．【分析】一位贫穷的农民用马驮着一袋麦子去镇上，在途中掉下来，但这个袋子太重了，他搬不动，他希望有人能来帮助他，后来一个法官帮助了他．【解答】1．A 考查动词的辨析．A．to do动词不定式B．do 动词原形C．doing 现在分词D．did 动词过去式；根据题干可知此处是特殊疑问词加不定式的结构，结合句意：当袋子从马上掉下来时，他不知道该怎么办．故选A．2．B 考查单词的辨析．A．so如此（修饰形容词）B．too非常C．such如此（修饰名词）D．very非常，根据后面的to lift，可知此处是固定句型too…to太…而不能，结合句意：这个袋子太重了，他搬不动，故选B．3．D 考查代词的辨析．A．any body任何人B．everybody每个人C．nobody没有人D．somebody某个人；根据上一句The bag was too heavy for him to lift这个袋子太重了，他提不起来，此处应该是：他希望有人能来帮助他，故选D．4．C 考查形容词的辨析．A．happy高兴的B．hungry 饥饿的C．sad悲伤的D．angry 生气的；根据下一句because he was the famous judge（法官）in town．The farmer was afraid to ask him for（55）因为他是镇上有名的法官，农夫不敢向他求助．此处应该是：但是农夫看到那个人时很不高兴，故选C．5．B 考查名词的辨析．A．advice 建议B．help 帮助C．money 钱D．wheat 小麦；根据上一句because he was the famous judge（法官）in town因为他是镇上有名的法官，此处应该是：农夫不敢向他求助，故选B．6．A 考查动词词组的辨析．A．got off下车，下马B．got out出去C．fell off 跌落D．got on 上车；根据下一句You need my help，don't you？Let me help you你需要我的帮助，不是吗？让我来帮你，此处应该是：法官从马上下来，故选A．7．D 考查单词的辨析．A．other 形容词，别的，表示泛指B．another 另一个C．others 名词，D．the other指两者中的另一个；根据上一句Then he took one end of the bag然后他抬起袋子的一端，此处应该是：农民抬起另一端，故选D．8．C 考查动词的辨析．A．dropped掉下来B．pushed推C．lifted 举起D．drew 画；根据上一句Then he took one end of the bag，and the farmer took（57），然后他抬起袋子的一端，农民抬起另一端，此处应该是：他们把那袋小麦抬到马背上，故选C．9．B 考查动词的辨析．A．call 打电话B．pay 付钱C．stand 站D．afford负担得起；根据上文Let me help you，可知法官帮助了农民，此处应该是：我怎么偿还你？故选B．10．A 考查连词的辨析．A．if 如果B．before 在…之前C．until 直到D．Though虽然；根据下一句do the same for him为他做同样的事，此处应该是：如果你看到有人需要帮助，故选A．17．【分析】文章大意：这是一篇记叙文，短文讲述的是作者在一个残疾人的学校里帮助那里的孩子，其中有一个叫Nancy的女孩，她的一只手不能动．但是她通过自己的努力，做到了自己想做的事情．因此我们应该鼓励人们去做自己想做的事情．【解答】1．C．动词及语境的理解．句意：我被选去一个残疾人学校工作．read 读，阅读；study 学习；work工作；visit参观．根据Years ago，while I lived in England，part of my college task was to help the children with special needs可知，作者上大学时的一个任务就是帮助有特殊需要的孩子．因此这里作者是去一个残疾人学校，去帮助那里的孩子，所以是去那里工作．故选C．2．A．动词短语及语境的理解．句意：老师让我去照顾Nancy，一个十岁的女孩．look after 照顾；look for 寻找；look at 看；look over 复习．根据I was chosen to work in a school with disabled children．可知，我工作的地点是一所残疾儿童学校，可以推测这里老师让我去照顾Nancy这个残疾女孩．故选A．3．B．代词及语境的理解．句意：她的一只手不能动．his 他的；her 她的；my 我的；your 你的．根据The teacher asked me to﹣﹣Nancy，a ten﹣year﹣old girl．可知，作者照顾的是Nancy，一个十岁的女孩，故这里应该用her．故选B．4．C．连词及语境的理解．句意：如果Nancy能自己穿上衣服，学校里的老师们就会认为这是一个伟大的成就．before 在…之前；through 穿过，通过；if 如果；until 直到…时候．根据One of﹣﹣hands could not move．可知，Nancy的一只手不能动，是一个残疾人，因此穿衣服这样的事情对她来说也是很困难的．因此如果她能自己穿上衣服，这就是了不起的事了．故这里表示的是条件．故选C．5．A．介词及语境的理解．句意：但是我在她身上看到了更多．她一直想把一根细绳穿过钥匙洞．through 穿过，通过，指在物体的中间穿过；across 穿过，指从表面穿过；over 在…上面，覆盖；into到…里面．根据She had always wanted to put a string﹣﹣the hole of a key．可知，这里是指在钥匙洞里穿过，指从内部穿过，因此用through．故选A．6．D．动词及语境的理解．句意：在Nancy在这所学校的5年中，老师们总是想要帮助她，但是最后却是替她做了所有的工作．fail 失败；refuse 拒绝；agree 同意；try尽力．这四个动词的后面都可以跟动词不定式，但是根据For the 5 years Nancy was in the school，the teachers always﹣﹣to help her可知，老师们尽力的去帮助她．故选D．7．B．代词及语境的理解．句意：我知道Nancy可以做的更多，所以我鼓励她自己做事情．less 更少；more 更多；nothing 没什么事；anything任何事．根据I knew Nancy could do﹣﹣，so I encouraged her to do something herself．可知，学校的老师们总以为Nancy 自己做不到一些事情，但是我却认为Nancy能做到的事情比我们想象的更多，所以才鼓励她自己做事情．故选B．8．D．形容词及语境的理解．句意：开始的时候，Nancy经常失败，变得很不开心．excited 兴奋的，激动的；pleased 高兴的；unsafe 不安全的；unhappy 不开心的．根据At first Nancy often failed and got very﹣﹣可知，Nancy因为失败会变得不开心．故选D．9．B．连词及语境的理解．句意：有时候我也想放弃了，然而，一周后，Nancy做到了。

第十八章卷（2）一、选择题1．如图，已知四边形ABCD是平行四边形，下列结论中不正确的是（）A．当AB=BC时，它是菱形B．当AC⊥BD时，它是菱形C．当∠ABC=90°时，它是矩形D．当AC=BD时，它是正方形2．下列命题中正确的是（）A．对角线互相平分的四边形是菱形B．对角线互相平分且相等的四边形是菱C．对角线互相垂直的四边形是菱形D．对角线互相垂直平分的四边形是菱形3．如图，某花木场有一块等腰梯形ABCD的空地，其各边的中点分别是E、F、G、H，测得对角线AC=10m，现想利用篱笆围成四边形EFGH场地，则需篱笆得总长度是（）A．40 m B．30 m C．20 m D．10 m4．在梯形ABCD中，AD∥BC，对角线AC⊥BD，且AC=10，BD=6，则该梯形的面积是（）A．30 B．15 C．D．605．如图，已知矩形ABCD中，R、P分别是DC、BC上的点，E、F分别是AP、RP 的中点，当P在BC上从B向C移动而R不动时，那么下列结论成立的是（）A．线段EF的长逐渐增大B．线段EF的长逐渐减小C．线段EF的长不改变D．线段EF的长不能确定6．已知一个直角梯形，一腰长为6，这腰与一底所成的角为30°，那么另一腰的长是（）A．1.5 B．3 C．6 D．97．如图所示，将一张正方形纸片对折两次，然后在上面打3个洞，则纸片展开后是（）A．B．C．D．8．用两个全等的直角三角形拼下列图形：①矩形；②菱形；③正方形；④平行四边形；⑤等腰三角形；⑥等腰梯形．其中一定能拼成的图形是（）A．①②③B．①④⑤C．①②⑤D．②⑤⑥二、填空题9．如图，在平行四边形ABCD中，DB=DC，∠C=70°，AE⊥BD于E，则∠DAE=度．10．如图，点E、F在▱ABCD的对角线BD上，要使四边形AECF是平行四边形，还需添加一个条件．（只需写出一个结论，不必考虑所有情况）．11．如图所示，工人师傅做铝合金窗框分下面三个步骤进行：(1)先截出两对符合规格的铝合金窗料（如图①所示），使AB=CD，EF=GH．(2)摆放成如图②的四边形，则这时窗框的形状是，根据的数学道理是．(3)将直尺紧靠窗框的一个角（如图③），调整窗框的边框，当直角尺的两条直角边与窗框无缝隙时（如图④，说明窗框合格，这时窗框是，根据的数学道理是．12．如图，菱形ABCD中，AC=2，BD=5，P是AC上一动点（P不与A、C重合），PE∥BC交AB于E，PF∥CD交AD于F，则图中阴影部分（即多边形BCPFEB）的面积为．13．如图所示，菱形ABCD中，对角线AC，BD相交于点O，若再补充一个条件能使菱形ABCD成为正方形，则这个条件是．（只填一个条件即可，答案不唯一）14．等腰梯形两底之差为12cm，高为6cm，则其锐角底角为度．15．若矩形的对角线长为8cm，两条对角线的一个交角为60°，则该矩形的面积为cm2．三、解答题16．已知：如图，在梯形ABCD中，AD∥BC，CD=10cm，∠B=45度，∠C=30度，AD=5cm．求：(1)AB的长；(2)梯形ABCD的面积．17．如图，在菱形ABCD中，∠A与∠B的度数比为1：2，周长是48cm．求：(1)两条对角线的长度；(2)菱形的面积．18．如图，在平行四边形ABCD中，E、F是AC上的两点，且AE=CF．求证：DE=BF．19．如图，在梯形ABCD中，AD∥BC，AB∥DE，AF∥DC，E、F两点在边BC上，且四边形AEFD是平行四边形．(1)AD与BC有何等量关系，请说明理由；(2)当AB=DC时，求证：平行四边形AEFD是矩形．20．如图，△ABC中，AC的垂直平分线MN交AB于点D，交AC于点O，CE∥AB交MN于E，连接AE、CD．请判断四边形ADCE的形状，说明理由．答案1．如图，已知四边形ABCD是平行四边形，下列结论中不正确的是（）A．当AB=BC时，它是菱形B．当AC⊥BD时，它是菱形C．当∠ABC=90°时，它是矩形D．当AC=BD时，它是正方形【考点】正方形的判定；平行四边形的性质；菱形的判定；矩形的判定．【专题】选择题．【分析】根据邻边相等的平行四边形是菱形；根据所给条件可以证出邻边相等；根据有一个角是直角的平行四边形是矩形；根据对角线相等的平行四边形是矩形．【解答】解：A、根据邻边相等的平行四边形是菱形可知：四边形ABCD是平行四边形，当AB=BC时，它是菱形，故A选项正确；B、∵四边形ABCD是平行四边形，∴BO=OD，∵AC⊥BD，∴AB2=BO2+AO2，AD2=DO2+AO2，∴AB=AD，∴四边形ABCD是菱形，故B选项正确；C、有一个角是直角的平行四边形是矩形，故C选项正确；D、根据对角线相等的平行四边形是矩形可知当AC=BD时，它是矩形，不是正方形，故D选项错误；综上所述，符合题意是D选项；故选D．【点评】此题主要考查学生对正方形的判定、平行四边形的性质、菱形的判定和矩形的判定的理解和掌握，此题涉及到的知识点较多，学生答题时容易出错．2．下列命题中正确的是（）A．对角线互相平分的四边形是菱形B．对角线互相平分且相等的四边形是菱C．对角线互相垂直的四边形是菱形D．对角线互相垂直平分的四边形是菱形【考点】菱形的判定．【专题】选择题．【分析】对角线互相垂直平分的四边形是菱形．【解答】解：根据菱形的判定，知对角线互相垂直平分的四边形是菱形，A、B、C错误，D正确．故选D．【点评】本题考查菱形的判定方法．3．如图，某花木场有一块等腰梯形ABCD的空地，其各边的中点分别是E、F、G、H，测得对角线AC=10m，现想利用篱笆围成四边形EFGH场地，则需篱笆得总长度是（）A．40 m B．30 m C．20 m D．10 m【考点】三角形中位线定理．【专题】选择题．【分析】据等腰梯形的性质和三角形的中位线定理有EF=GH=AC，EH=GF=BD，可知四边形EFGH的周长=4EF=2AC，进而可得出四边形EFGH的周长，即需篱笆得总长．【解答】解：如图，连接BD，∵E、F、G、H是等腰梯形ABCD各边中点，∴EF=GH=AC，EH=GF=BD，∵等腰梯形ABCD，∴BD=AC，∴四边形EFGH的周长=4EF=2AC=20m．故选C．【点评】此题主要考查了等腰梯形的性质和三角形中位线定理，得出四边形EFGH的周长与AC 的关系是解题的关键，难度一般．4．在梯形ABCD 中，AD ∥BC ，对角线AC ⊥BD ，且AC=10，BD=6，则该梯形的面积是（ ） A ．30 B ．15 C ．D ．60【考点】根据边的关系判定平行四边形． 【专题】选择题．【分析】根据对角线互相垂直的四边形的面积公式，得该梯形的面积是10×6÷2=30．【解答】解：如图，作DE ∥AC 交BC 延长线于E∵AD ∥BC∴四边形ADEC 为平行四边形 ∴CE=AD ，∠CDE=∠DCA ∵AC ⊥BD ， ∴AC ⊥DE ，∴△BDE 为直角三角形， ∴S 梯ABCD =S △EBD ，∴S 梯ABCD =DE•BD=AC•BD=10×6÷2=30， 故选A ．【点评】根据三角形的面积公式可以导出：对角线互相垂直的四边形的面积等于两条对角线乘积的一半．5．如图，已知矩形ABCD 中，R 、P 分别是DC 、BC 上的点，E 、F 分别是AP 、RP 的中点，当P 在BC 上从B 向C 移动而R 不动时，那么下列结论成立的是（ ）A．线段EF的长逐渐增大B．线段EF的长逐渐减小C．线段EF的长不改变D．线段EF的长不能确定【考点】三角形中位线定理．【专题】选择题．【分析】因为R不动，所以AR不变．根据中位线定理，EF不变．【解答】解：连接AR．因为E、F分别是AP、RP的中点，则EF为△APR的中位线，所以EF=AR，为定值．所以线段EF的长不改变．故选C．【点评】本题考查了三角形的中位线定理，只要三角形的边AR不变，则对应的中位线的长度就不变．6．已知一个直角梯形，一腰长为6，这腰与一底所成的角为30°，那么另一腰的长是（）A．1.5 B．3 C．6 D．9【考点】根据边的关系判定平行四边形．【专题】选择题．【分析】作梯形的另一高，则得一个矩形和一个30°的直角三角形，根据直角三角形中，30°所对的直角边是斜边的一半，得另一腰是已知腰的，即是3．【解答】解：作DE⊥BC，∵AD∥BC，∴四边形ABED为平行四边形，∴AB=DE，又∠C=30°，∴DE=DC=3．故选B．【点评】注意：直角梯形中常见的辅助线即作另一高．熟练运用30°的直角三角形的性质．7．如图所示，将一张正方形纸片对折两次，然后在上面打3个洞，则纸片展开后是（）A．B．C．D．【考点】正方形的性质．【专题】选择题．【分析】结合空间思维，分析折叠的过程及打孔的位置，易知展开的形状．【解答】解：当正方形纸片两次沿对角线对折成为一直角三角形时，在平行于斜边的位置上打3个洞，则直角顶点处完好，即原正方形中间无损，且有12个洞．故选D．【点评】本题主要考查学生抽象思维能力，错误的主要原因是空间观念以及转化的能力不强，缺乏逻辑推理能力，需要在平时生活中多加培养．8．用两个全等的直角三角形拼下列图形：①矩形；②菱形；③正方形；④平行四边形；⑤等腰三角形；⑥等腰梯形．其中一定能拼成的图形是（）A．①②③B．①④⑤C．①②⑤D．②⑤⑥【考点】菱形的判定；等腰三角形的判定；平行四边形的判定；矩形的判定；正方形的判定；等腰梯形的判定．【专题】选择题．【分析】根据菱形、正方形、梯形、矩形、平行四边形、等腰三角形的性质判断．【解答】解：由于菱形和正方形中都四边相等的特点，而直角三角形中不一定有两边相等，故两个全等的直角三角形不能拼成菱形和正方形；由于等腰梯形有两边不等，故也不能．矩形，平行四边形，等腰三角形可以拼成．如图：故选B．【点评】本题考查了三角形的拼接图形的特点．以及特殊四边形的性质．9．如图，在平行四边形ABCD中，DB=DC，∠C=70°，AE⊥BD于E，则∠DAE=度．【考点】平行四边形的性质．【专题】填空题．【分析】由DB=DC，∠C=70°可以得到∠DBC=∠C=70°，又由AD∥BC推出∠ADB=∠DBC=∠C=70°，而∠AED=90°，由此可以求出∠DAE．【解答】解：∵DB=DC，∠C=70°，∴∠DBC=∠C=70°，∵AD∥BC，AE⊥BD，∴∠ADB=∠DBC=∠C=70°，∠AED=90°，∴∠DAE=90﹣70=20°．故答案为：20°．【点评】主要考查了平行四边形的基本性质，并利用性质解题．平行四边形基本性质：①平行四边形两组对边分别平行；②平行四边形的两组对边分别相等；③平行四边形的两组对角分别相等；④平行四边形的对角线互相平分．10．如图，点E、F在▱ABCD的对角线BD上，要使四边形AECF是平行四边形，还需添加一个条件．（只需写出一个结论，不必考虑所有情况）．【考点】平行四边形的判定与性质．【专题】填空题．【分析】使四边形AECF也是平行四边形，则要证四边形的两组对边相等，或两组对边分别平行，可添加条件DF=BE．【解答】解：需要添加的条件可以是：DF=BE．理由如下：∵四边形ABCD是平行四边形，∴AD∥BC，BC=AD，∴∠CBE=∠ADF，在△ADF与△BCE中，，∴△ADF≌△BCE（SAS），∴CE=AF，同理，△ABE≌△CDF，∴CF=AE，∴四边形AECF是平行四边形．【点评】此题主要考查了平行四边形的判定以及矩形的判定方法，此题属于开放题熟练掌握各判定定理是解题的关键．11．如图所示，工人师傅做铝合金窗框分下面三个步骤进行：(1)先截出两对符合规格的铝合金窗料（如图①所示），使AB=CD，EF=GH．(2)摆放成如图②的四边形，则这时窗框的形状是，根据的数学道理是．(3)将直尺紧靠窗框的一个角（如图③），调整窗框的边框，当直角尺的两条直角边与窗框无缝隙时（如图④，说明窗框合格，这时窗框是，根据的数学道理是．【考点】平行四边形的判定；矩形的判定．【专题】填空题．【分析】此题主要考查平行四边形，矩形的判定问题，掌握其判定定理，即可作答．【解答】解：平行四边形；两组对边分别相等的四边形是平行四边形；矩形；由一个角是直角的平行四边形是矩形．【点评】熟练掌握平行四边形及矩形的判定．12．如图，菱形ABCD中，AC=2，BD=5，P是AC上一动点（P不与A、C重合），PE∥BC交AB于E，PF∥CD交AD于F，则图中阴影部分（即多边形BCPFEB）的面积为．【考点】菱形的性质．【专题】填空题．【分析】根据菱形性质得出AC⊥BD，求出△ABC的面积，求出△AEF的面积和△PEF的面积相等，得出阴影部分的面积等于三角形ABC的面积，即可得出答案．【解答】解：∵四边形ABCD是菱形，∴AC⊥BD，BO=OD=BD=2.5，∴△ABC的面积是×AC×BO=2.5，∵AD∥BC，AB∥DC，又∵PE∥BC，PF∥CD，∴PF∥AB，PE∥AD，∴四边形AEPF是平行四边形，∴△AEF的面积和△PEF的面积相等，∴阴影部分的面积等于△ABC的面积是2.5．故答案为：2.5．【点评】本题考查了菱形的性质，三角形的面积，平行四边形的性质和判定等知识点的应用．13．如图所示，菱形ABCD中，对角线AC，BD相交于点O，若再补充一个条件能使菱形ABCD成为正方形，则这个条件是．（只填一个条件即可，答案不唯一）【考点】正方形的判定；菱形的性质．【专题】填空题．【分析】根据菱形的性质及正方形的判定来添加合适的条件．【解答】解：要使菱形成为正方形，只要菱形满足以下条件之一即可，(1)有一个内角是直角(2)对角线相等．即∠BAD=90°或AC=BD．故答案为：∠BAD=90°或AC=BD．【点评】本题比较容易，考查特殊四边形的判定．14．等腰梯形两底之差为12cm，高为6cm，则其锐角底角为度．【考点】根据边的关系判定平行四边形．【专题】填空题．【分析】先作图，过点D作DE∥AB，四边形ABED是平行四边形，根据题意得CE=12cm，△CDE是等腰三角形，从而得出DF=CF=6cm，则锐角底角为45°．【解答】解：过点D作DE∥AB，∵AD∥BC，∴四边形ABED是平行四边形，∴AB=DE，∵AB=CD，∴DE=CD，∴△CDE是等腰三角形，又DF⊥CE，∴EF=CF=CE=（BC﹣AD）=6cm，∵高DF=6cm，∴DF=CF=6cm，而∠DFC=90°，∴∠DCF=45°．【点评】本题考查了梯形中辅助线的作法：平移一腰得出两底之差，还考查了等腰三角形的性质．15．若矩形的对角线长为8cm，两条对角线的一个交角为60°，则该矩形的面积为cm2．【考点】矩形的性质．【专题】填空题．【分析】根据矩形的性质，画出图形求解．【解答】解：∵ABCD为矩形∴OA=OC=OB=OD∵一个角是60°∴BC=OB=cm∴根据勾股定理==∴面积=BC•CD=4×=cm2．故答案为．【点评】本题考查的知识点有：矩形的性质、勾股定理．16．已知：如图，在梯形ABCD中，AD∥BC，CD=10cm，∠B=45度，∠C=30度，AD=5cm．求：(1)AB的长；(2)梯形ABCD的面积．【考点】矩形的判定定理2．【专题】解答题．【分析】(1)过点D作DE⊥BC于E，根据30°角所对的直角边等于斜边的一半可得DE=CD，再判断△ABH是等腰直角三角形，然后根据等腰直角三角形斜边等于直角边的倍解答；(2)先判定四边形AHED是矩形，根据矩形对边相等求出HE=AD，再求出BC的长，然后根据梯形的面积公式列式进行计算即可得解．【解答】解：(1)如图，过点D作DE⊥BC于E，∵∠C=30°，CD=10cm，∴DE=CD=×10=5cm，过A作AH⊥BC于H，则AH=DE=5cm，∵∠B=45°，∴△ABH是等腰直角三角形，∴AB=AH=5cm；(2)∵AH、DE都是梯形的高线，∴四边形AHED是矩形，∴HE=AD=5cm，又∵BH=AH=5cm，CE===5cm，∴BC=BH+HE+CE=5+5+5=（10+5）cm，∴梯形ABCD的面积=（5+10+5）×5=（+）cm．【点评】本题考查了梯形的性质，直角三角形30°角所对的直角边等于斜边的一半的性质，等腰直角三角形的判定与性质，勾股定理的应用，熟记性质并作出辅助线是解题的关键．17．如图，在菱形ABCD中，∠A与∠B的度数比为1：2，周长是48cm．求：(1)两条对角线的长度；(2)菱形的面积．【考点】菱形的性质．【专题】解答题．【分析】在菱形ABCD中，∠A与∠B互补，即∠A+∠B=180°，因为∠A与∠B的度数比为1：2，就可求出∠A=60°，∠B=120°，根据菱形的性质得到∠BDA=120°×=60°，则△ABD是正三角形，所以BD=AB=48×=12cm，根据勾股定理得到AC的值；然后根据菱形的面积公式求解．【解答】解：(1)连接BD，∵∠A与∠B互补，即∠A+∠B=180°，∠A与∠B的度数比为1：2，∴∠A=60°，∠B=120°．∴∠BDA=120°×=60°．∴△ABD是正三角形．∴BD=AB=48×=12cm．AC=2×=12cm．∴BD=12cm，AC=12cm．(2)S菱形ABCD=×两条对角线的乘积=×12×12=72cm2【点评】本题考查的是菱形的面积求法及菱形性质的综合．18．如图，在平行四边形ABCD中，E、F是AC上的两点，且AE=CF．求证：DE=BF．【考点】平行四边形的性质．【专题】解答题．【分析】由平行四边形的性质得AD=CB，∠DAE=∠BCF，再由已知条件，可得△ADE≌△CBF，进而得出结论．【解答】证明：在平行四边形ABCD中，则AD=CB，∠DAE=∠BCF，又AE=CF，∴△ADE≌△CBF（SAS），∴DE=BF．【点评】本题主要考查平行四边形的性质及全等三角形的判定问题，应熟练掌握．19．如图，在梯形ABCD中，AD∥BC，AB∥DE，AF∥DC，E、F两点在边BC上，且四边形AEFD是平行四边形．(1)AD与BC有何等量关系，请说明理由；(2)当AB=DC时，求证：平行四边形AEFD是矩形．【考点】平行四边形的性质；矩形的判定．【专题】解答题．【分析】(1)由题中所给平行线，不难得出四边形ABED和四边形AFCD都是平行四边形，而四边形AEFD也是平行四边形，三个平行四边形都共有一条边AD，所以可得出AD=BC的结论．(2)根据矩形的判定和定义，对角线相等的平行四边形是矩形．只要证明AF=DE 即可得出结论．【解答】(1)解：AD=BC．理由如下：∵AD∥BC，AB∥DE，AF∥DC，∴四边形ABED和四边形AFCD都是平行四边形．∴AD=BE，AD=FC，又∵四边形AEFD是平行四边形，∴AD=EF．∴AD=BE=EF=FC．∴AD=BC．(2)证明：∵四边形ABED和四边形AFCD都是平行四边形，∴DE=AB，AF=DC．∵AB=DC，∴DE=AF．又∵四边形AEFD是平行四边形，∴平行四边形AEFD是矩形．【点评】本题考查了梯形、平行四边形的性质和矩形的判定，是一道集众多四边形于一体的小综合题，难度中等稍偏上的考题．有的学生往往因为基础知识不扎实，做到一半就做不下去了，建议老师平时教学中，重视一题多变，适当地变式联系，可以触类旁通．20．如图，△ABC中，AC的垂直平分线MN交AB于点D，交AC于点O，CE∥AB交MN于E，连接AE、CD．请判断四边形ADCE的形状，说明理由．【考点】菱形的判定；线段垂直平分线的性质．【专题】解答题．【分析】根据中垂线的性质中垂线上的点线段两个端点的距离相等可得出AE=CE，AD=CD，OA=OC∠AOD=∠EOC=90°，再结合CE∥AB，可证得△ADO≌△CEO，从而根据由一组对边平行且相等知，四边形ADCE是平行四边形，结合OD=OE，OA=OC，∠AOD=90°可证得为菱形．【解答】四边形ADCE是菱形．证明：∵MN是AC的垂直平分线，∴AE=CE，AD=CD，OA=OC，∠AOD=∠EOC=90°，∵CE∥AB，∴∠DAO=∠ECO，∴△ADO≌△CEO．（ASA）∴AD=CE，OD=OE，∵OD=OE，OA=OC，∴四边形ADCE是平行四边形又∵∠AOD=90°，∴▱ADCE是菱形．【点评】本题考查了菱形的判定及线段垂直平分线的性质，利用了：中垂线的性质；全等三角形的判定和性质；平行四边形和菱形的判定．。

课题学习选择方案同步练习一、选择题1．6月份以来，猪肉价格一路上涨．为平抑猪肉价格，某省积极组织货源，计划由A、B、C三市分别组织10辆、10辆和8辆运输车向D、E两市运送猪肉，现决定派往D、E两地的运输车分别是18辆、10辆，已知一辆运输车从A市到D、E两市的运费分别是200元和800元，从B市到D、E两市的运费分别是300元和700元，从C市到D、E两市的运费分别是400元和500元．若设从A、B两市都派x辆车到D市，则当这28辆运输车全部派出时，总运费W（元）的最小值和最大值分别是（）A. 8000，13200B. 9000，10000C. 10000，13200D. 13200，154002．春节期间，某批发商欲将一批海产品由A地运往B地，汽车货运公司和铁路货运公司均开放海产品的运输业务，两货运公司的收费项目及收费标准如下表所示．已知运输路程为120千米，汽车和火车的速度分别为60千米/小时，100千米/小时，请你选择一种交通工具（）火车 1.8 5 0 1600 A. 当运输货物重量为60吨，选择汽车B. 当运输货物重量大于50吨，选择汽车C. 当运输货物重量小于50吨，选择火车D. 当运输货物重量大于50吨，选择火车3．某公司准备与汽车租凭公司签订租车合同，以每月用车路程xkm 计算，甲汽车租凭公司每月收取的租赁费为y1元，乙汽车租凭公司每月收取的租赁费为y2元，若y1、y2与x之间的函数关系如图3所示，其中x＝0对应的函数值为月固定租赁费，则下列判断错误的是（）A. 当月用车路程为2000km时，两家汽车租赁公司租赁费用相同B. 当月用车路程为2300km时，租赁乙汽车租赁公车比较合算C. 除去月固定租赁费，甲租赁公司每公里收取的费用比乙租赁公司多D. 甲租赁公司平均每公里收到的费用比乙租赁公司少4．一家游泳馆的游泳收费标准为30元/次，若购买会员年卡，可享受如下优惠：会员年卡类型办卡费用(元) 每次游泳收费(元)A类50 25B类200 20C类400 15例如，购买A类会员年卡，一年内游泳20次，消费50＋25×20＝550元，若一年内在该游泳馆游泳的次数介于45～55次之间，则最省钱的方式为( )A. 购买A类会员年卡B. 购买B类会员年卡C. 购买C类会员年卡D. 不购买会员年卡二、填空题5．小明家准备春节前举行80人的聚餐，需要去某餐馆订餐．据了解餐馆有10人坐和8人坐两种餐桌，要使所订的每个餐桌刚好坐满，则订餐方案共有_____种．6．某电信公司推出了A，B两种手机上网套餐，每种套餐一个月的手机上网费用y（元）与上网时间x（分钟）之间的关系如图，如果顾客一个月上网300分钟，那么选择套餐_______（填A或B）产生的费用比较高，高__________ 元。

人教版八年级生物下册第八单元第二、三章一、选择题(每小题2分,共50分)1.某人到药店购买某种药品,营业员却因其手续不全而拒售。

你认为此人欲购药品属于()A.非处方药B.处方药C.外用药D.内服药2.正确的用药方法是()A.买贵药和进口药疗效更好B.药吃得越多病好得越快C.可随意使用OTC类药品D.使用前阅读药品说明书3.小张患了感冒,以下用药方法正确的是()A.感冒糖浆很甜,可以多喝点B.用茶服药,可以促进人体对药物的吸收C.到医院请医生诊断,凭医生的处方到医院药房拿药D.当感冒病情减轻,就停止服药4.存放几种药物时,应注意()A.放在同一容器里B.放在干燥、避光、幼儿能拿到的地方C.放在干燥、阴凉、避光、幼儿拿不到的地方D.放在有阳光的地方,利用紫外线消毒5.关于安全用药的下列做法:①生病买药时首先明确病情、病因,②服药时可自己增加用量,③处方药可直接到药房购买,④用药前仔细阅读药品使用说明书。

正确的是()A.①④B.②③C.②④D.③④6.对如图1几种出血情况的判断和止血方法的运用完全正确的是()图1A.甲是静脉出血,用止血带压迫止血B.甲是动脉出血,用止血带压迫止血C.乙是动脉出血,用止血带压迫止血D.丙是静脉出血,用创可贴止血7. 抢救煤气中毒而昏厥的病人,不恰当的急救措施是()A.拨打“120”急救电话B.将病人转移到空气新鲜的地方C.若病人呼吸骤停,须原地等待医生救治D.让病人仰卧平躺,保持呼吸道畅通8.下列有关急救的叙述,错误的是()A.意外伤害动脉出血时,应在远心端止血B.生活中急需医疗救护时,拨打120C.火灾现场自救时,用湿毛巾捂住口鼻D.为急救车让行,搭建生命通道9.从2019年7月开始的澳大利亚火灾持续了近7个月,最让人心痛的是至少有23名扑火人员牺牲。

在救灾过程中,吸入较多的烟尘和二氧化碳,可能会导致人心跳、呼吸骤停,当遇到此种情况时,救护人员会立即将患者移到空气流通的地方,并立即开始“心肺复苏”。

八年级英语下册Unit 2 I’ll help to clean up the city parks单元测试题(45分钟100分)第Ⅰ卷(共50分)Ⅰ. 听力(10分)（略）Ⅰ. 单项选择(10分)( )1. Let's go to see the sick kids and ________.A．cheer them up B．cheer up themC．clean up them D．fix them up( )2. If you do your best, I'm sure you'll ________ do it well.A．can B．couldC．are able to D．be able to( )3. He didn't use to ________ soccer, but now he likes ________ it.A．playing, playing B．play, playingC．playing, to play D．plays, to play( )4. He's always ________ at home, but he doesn't feel________.A．alone, alone B．lonely, lonelyC．alone, lonely D．lonely, alone( )5. We were all ________ to hear the ________ news.A．excited, excited B．exciting, excitingC．excited, exciting D．exciting, excited( )6. Scientists are trying their best to ways to treat the terrible disease called H7N9.A. come up withB. look forward toC. talk aboutD. give up( )7. The students are notices to people over there to ask them to protect our earth.A. printing outB. giving outC. selling outD. putting out( )8. Jack’s teacher asked him the lights after class.A. turning offB. turned offC. to turn offD.turn off( )9. —Excuse me. Could you please tell me my car?—Sure. Park it right here. I’ll help you.A. where parkB. where to parkC. to park whereD. when to park( )10. —Could you look after parrots for me while we’re away?—.A. Yes, pleaseB. No, I’m notC. With pleasureD. You’re welcomeⅠ. 完形填空(10分)Bill, a thirteen-year-old boy, thought he had grown up to be a man. But his parents told him, “You won’t be a real man until you begin to1helping others. ”One morning, his parents gave him some money to2some milk for them. Outside a shop he saw a homeless old man who looked very3. Bill went to him and asked, “What’s wrong with you? ”The old man answered, “I’m hungry. I haven’t had any food for two days. ”At the thought of his parents’ words, Bill said to the old man, “Let’s go to the4. ”When they got there, Bill asked the waiter to bring out bread and coffee to the old man. The old man finished the meal quickly. After the waiter5the plate and the cup, the old man said, “Sorry for giving you so much6. I’m fine now. I’ll7forget your kindness! You are a very good young man. ”Bill was8when he heard this. Just when he wanted to pay for the meal, the waiter came. Bill and the old man learned9that the food was free10it was the birthday of the boss, and they were the first customers(顾客)that day.( )1. A. think about B. depend on C. give up D. go on( )2. A. lend B. buy C. drink D. borrow( )3. A. afraid B. glad C. sick D. angry( )4. A. bank B. library C. hospital D. restaurant( )5. A. sent out B. got down C. gave back D. took away( )6. A. excuse B. advice C. trouble D. difficulty( )7. A. never B. always C. usually D. sometimes( )8. A. nervous B. pleased C. sorry D. shy( )9. A. in surprise B. as usual C. once again D. at first( )10. A. when B. until C. unless D. becauseⅠ. 阅读理解(20分)A few weeks ago, a friend from an unknown Smile Groups sent me $120 to do good things with. Since then I have used the money in the U. K. and U. S. It has helped families and strangers, and generally raised a lot of smiles. They have warmed my heart, but none so much as the gift I was able to give just an hour ago.I was in a charity shop, looking at the second-hand books. It happened that the bookshelves were next to the toy shelf. I noticed a group of poorly dressed women standing behind me. As they looked through the clothes shelf, a little girl about three years old came over to the toy shelf. Immediately her attention was caught by a toy pram(手推车). She spoke to her mother and her mother asked the shop assistant how much it cost. $3 was the answer.The mum looked down at her child, perhaps thinking what she still had to buy and how much money she would have left. Then she shook her head. The child didn’t behave(表现)as badly as some might. Being told “no” was not new for her but she couldn’t keep the disappointment(失望)from her face.I had a total of $5 in my pocket. I touched the mother on the shoulder, put the money in her hand and said, “Buy her a doll too. ”I didn’t wait to see the end. After all, it was not about being thanked. I walked out of the shop and into the sunshine.The money the friend gave me was to help me find happiness of the world. Was there any better way, I wondered, to get so much happiness for so little money than to buy a little girl a toy pram and a doll to sit in it?( )1. Where did the story take place?A. In a Smile Groups.B. In a toy shop.C. In a charity shop.D. In a book shop.( )2. According to the passage, the writer used the money given by his friend.A. to thank his friend for his helpB. to do some shoppingC. to donate to a charity organizationD. to make a donation in happiness( )3. When her mum refused to buy her the toy, the girl didn’t behave badly.A. because she didn’t want to behave badly in publicB. because she knew her mother didn’t have enough moneyC. because she was afraid her mother would be angryD. because she had got used to being refused( )4. The reason why the writer didn’t wait to see the end was that.A. he had no money thenB. he had already finished his taskC. he was afraid the woman might thank him very muchD. he was in a hurry第Ⅰ卷(共50分)Ⅰ. 词汇运用(20分)(Ⅰ)根据句意及首字母或汉语提示完成单词。

Unit 2 单元测试题(满分100)一. 单项选择(每小题1分，共15分)从A、B、C、D四个选项中选择可以填入空白处的最佳答案。

( )1. Changing schools made a big difference ______ his life.A. onB. atC. toD. foro travel around the world.( )2. Mary’s uncle made ______ possible for her tA. itB. thatC. thisD. one( )3. The girl is ______, so she needs a guide dog to help her.A. sickB. blindC. tiredD. sad( )4. My friend Tom volunteered ______ in the countryside two years ago.A. to workB. workC. workingD. works( )5. —Excuse me, I ______ find my hotel.—You could ask the policeman.A. can’tB. mustn’ｔC. needn’ｔD. shouldn’ｔ( )6. She used to ______ a bike to school, but now she is used to ______ to school.A. ride; walkB. riding; walkingC. riding; walkD. ride; walking( )7. He is very ______, so he can carry the heavy box.A. cleverB. strongC. quietD. excited( )8. —Who is the ______ of the house?—Mr. Black. He bought it last year.A. passengerB. guestC. visitorD. owner( )9. ______ vacations by the sea is Dale’s dream.A. SpendB. SpendingC. SpendsD. Spent( )10. They often help ______ sick children in the children’s hospital.A. cheer upB. clean upC. set upD. make up( )11. My cousin has difficulty ______ English newspapers.A. readB. readsC. readingD. to read( )12. My computer doesn’t work. Could you help ______ it?A. repairB. buyC. raiseD. open( )13. How nice these pictures are! Please _______ on the wall.A. put it upB. put up itC. put up themD. put them up( )14. I can help my mother do some things like ______ the rooms.A. cleansB. cleaningC. cleanD. to clean( )15. —We shouldn’t read in the sun.—______. It’s bad for our eyes.A. Sorry to hear thatB. That sounds greatC. You’re rightD. I don’t think so二. 完形填空(每小题1分，共10分)先通读下面的短文，掌握其大意，然后从A、B、C、D四个选项中选出可以填入空白处的最佳答案。