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tpo52阅读-3Early Food Production in Sub-Saharan Africa原文 (1)译文 (3)题目 (4)答案 (8)背景知识 (11)原文Early Food Production in Sub-Saharan Africa①At the end of the Pleistocene (around 10,000 B.C.), the technologies of food production may have already been employed on the fringes of the rain forests of western and central Africa, where the common use of such root plants as the African yam led people to recognize the advantages of growing their own food. The yam can easily be resprouted if the top is replanted. This primitive form of "vegeculture" (cultivation of root and tree crops) may have been the economic tradition onto which the cultivation of summer rainfall cereal crops was grafted as it came into use south of the grassland areas on the Sahara's southern borders.②As the Sahara dried up after 5000 B.C., pastoral peoples (cattle herders) moved southward along major watercourses into the savanna belt of West Africa and the Sudan. By 3000 B.C., just as ancient Egyptian civilization was coming into being along the Nile, they had settled in the heart of the East African highlands far to the south. The East African highlands are ideal cattle country and the home today of such famous cattle-herding peoples as the Masai. The highlands were inhabited byhunter-gatherers living around mountains near the plains until about 3300 B.C., when the first cattle herders appeared. These cattle people may have moved between fixed settlements during the wet and dry seasons, living off hunting in the dry months and their own livestock and agriculture during the rains.③As was the case elsewhere, cattle were demanding animals in Africa. They required water at least every 24 hours and large tracts of grazing grass if herds of any size were to be maintained. The secret was the careful selection of grazing land, especially in environments where seasonal rainfall led to marked differences in graze quality throughout the year. Even modest cattle herds required plenty of land and considerable mobility. To acquire such land often required moving herds considerable distances, even from summer to winter pastures. At the same time, the cattle owners had to graze their stock in tsetse-fly-free areas The only protection against human and animal sleeping sickness, a disease carried by the tsetse fly, was to avoid settling or farming such areas - a constraint severely limiting the movements of cattle-owning farmers in eastern and central Africa. As a result, small cattle herds spread south rapidly in areas where they could be grazed. Long before cereal agriculture took hold far south of the Sahara, some hunter-gatherer groups in the savanna woodlands of eastern and southern Africa may have acquired cattle, and perhaps other domesticated animals, by gift exchange or through raids on herding neighbors.④Contrary to popular belief: there is no such phenomenon as "pure" pastoralists,a society that subsists on its herds alone. The Saharan herders who moved southward to escape drought were almost certainly also cultivating sorghum, millet; and other tropical rainfall crops. By 1500 B.C., cereal agriculture was widespread throughout the savanna belt south of the Sahara. Small farming communities dotted the grasslands and forest margins of eastern West Africa, all of them depending on what is called shifting agriculture. This form of agriculture involved clearing woodland, burning the felled brush over the cleared plot, mixing the ash into the soil, and then cultivating the prepared fields. After a few years, the soil was exhausted, so the farmer moved on, exploiting new woodland and leaving the abandoned fields to lie fallow. Shifting agriculture, often called slash-and-burn, was highly adaptive for savanna farmers without plows, for it allowed cereal farming with the minimal expenditure of energy.⑤The process of clearance and burning may have seemed haphazard to the uninformed eye, but it was not. Except in favored areas, such as regularly inundated floodplains: tropical Africa's soils were of only moderate to low fertility. The art of farming was careful soil selection, that is, knowing which soils were light and easily cultivable, could be readily turned with small hoes, and would maintain their fertility over several years' planting, for cereal crops rapidly remove nitrogen and other nutrients from the soil. Once it had taken hold: slash-and-burn agriculture expanded its frontiers rapidly as village after village took up new lands,moving forward so rapidly that one expert has estimated it took a mere two centuries to cover 2,000 kilometers from eastern to southern Africa.译文撒哈拉以南非洲的早期粮食生产①更新世末期（大约公元前10000年），人们或许已经在非洲西部和中部的热带雨林周边运用粮食生产技术，例如非洲山药等根茎植物在这些地区的普遍种植使人们意识到粮食种植的优势。
TPO-52-L21.What is the lecture mainly about?A. A new approach to ensuring the survival of a forest ecosystemB. Similarities between desert and forest-stream ecosystemsC. Interactions that take place within a North American forest ecosystemD. Factors that have contributed to the preservation of salmon populations in forest ecosystems2.Why does the professor mention ants and rodents competing for food?A. To make sure the students understand the different components of an ecosystemB. To point out the limited resources available to organisms in a desert ecosystemC. To illustrate how different species adapt to extreme temperaturesD. To provide an example of an easily understood interaction within an ecosystem3.According to the professor, how do trees contribute to the successful spawning of salmon? [Click on 2 answers]A. They provide streams with nutrients that the salmon need.B. They provide shade that keeps streams sufficiently cool.C. They help salmon avoid predators by providing camouflage.D. They reduce the amount of sediment entering streambeds.4.What point does the professor make about bears carrying salmon away from streams?A. It results in bears eating fewer fish.B. It reduces the amount of food available to scavengers.C. It improves the health of the surrounding trees.D. It improves the water quality of the streams.5.What does the professor imply about overfishing?A. It is one of several reasons that the bear population has declined.B. It is difficult to prevent in both oceans and streams.C. It cannot be the sole focus for those working to prevent salmon depletion.D. Its impact is minor compared to the problems caused by logging.6.Why does one of the students say this:A. To provide support for a hypothesis mentioned by the professorB. To suggest that a bear behavior mentioned by the professor seems improbableC. To explain why confrontations take place between bearsD. To explain why bears eat so much in a short time spanAnswers：C/D/BD/C/C/BInteractions within an EcosystemListen to part of a lecture in an environmental science class.Professor:Today we are going to begin discussing ecosystems. One important point I want to emphasize in the reading is that there are many interactions that take place within an ecosystem, interactions between animals, interactions between living and non-living things and so on. Now these interactions can be fairly simple and straightforward.Ah, there are certain species of ants and rodents sharing a desert ecosystem in Arizona. And they compete for the same plants to eat. And the competition influence is not only the size of the ant and rodent populations, but also the number of eventual plants. Now, this interaction is easy to see, right? However, there are many other interactions within ecosystems that are not so apparent and require closer examination. And the example from your reading was the forest ecosystem along the Pacific coast of North America. Um, specifically the role of salmon.Ok, as you probably know, salmon are born in fresh water streams, they might ran to oceans where they spent most of their lives. And then they return to the same streams where they were born to reproduce, or spawn. In order to spawn, salmon need cold, clear streams to ensure the survival of their eggs. And trees in the surrounding forest play an important role here. Their leaves provide shade from the Sun. When logging removes the trees, the streams are open to the Sun and the water becomes warmer. When the water warms up, the concentration of dissolved oxygen in the water decreases. And this reduces the chance that the salmon eggs will survive.And the trees also help keep the soil on the banks of the stream in place. Salmon cannot spawn in streambeds clogged with sediment, dirt, from the surrounding area. They need a clean, graveled streambed.Bred?Bred:I read that salmon also help keep stream healthy.Professor:Right. Salmon contribute important nutrients like carbon and phosphorus. And these nutrients promote diversity in the stream environment.Ok, um, so salmon need trees to successfully reproduce, but surprisingly trees also need salmon. And bears play an important intermediary role. So in the autumn, bears are busy putting on extra-weight as they prepare to hibernate. Each bear catches an estimated 700 fish during the 45 days that the salmon are spawning.The bears catch the salmon in the streams and then they carry them back into the forest toeat. Sometimes as much as 800 meters from the streams. And since the bears only eat about half of each fish they catch, other animals like eagles, crows and insects feed on the leftovers.Maria?Maria:Why did the bears bring the salmon so far into the forest? Why not just eat the fish near the streams?Professor:Well, imagine several hungry bears looking for salmon. When one bear catches a fish, it’s not uncommon for another bear to try stealing it. These confrontations can be pretty intense. So it’s safer to bring it back into the forest, to a place where the bear can eat undisturbed.Bred:Um, you said that the bears only eat half of each fish they catch? I mean if I were a bear preparing to hibernate, I probably eat everything I can catch.Professor:Well, certain parts of a salmon are more nourishing, fattier than others. It’s actually more efficient for a bear to only eat some parts of the fish and then try catching another one, instead of eating the whole fish.O k. So after the scavengers have eaten the leftovers, only the fish’s skeleton remains. Now, salmon contain nitrogen. So their decomposing bodies as skeletons provide a lot of nitrogen to the surrounding forest. Plants absorb this nitrogen which they need to grow. So the transfer of this nitrogen to the forest is important. Forest near streams with salmon actually reach maturity faster than other forests.Ok, so, why’s all these important? Well, salmon are in trouble. Some of their populations have gone extinct. And most of the remaining populations have been significantly reduced by overfishing and environmental challenges. Now, conservationists can try to prevent overfishing but, well, I mean you can see the interconnections within this ecosystem. We’ve alr eady talked about the importance of trees to salmon and the negative effect that something like logging can have. So you can see that protecting this ecosystem is going to take a broad effort.。
托福听力tpo52section2对话讲座原文+题目+答案+译文Conversation2 (1)原文 (1)题目 (3)答案 (5)译文 (5)Lecture3 (7)原文 (7)题目 (9)答案 (11)译文 (11)Lecture4 (13)原文 (13)题目 (15)答案 (17)译文 (17)Conversation2原文NARRATOR:Listen to part of a conversation between a student and an employee at the campus store.FEMALE STUDENT:I like those ceramic coffee mugs you have on display at the other end of the store.Were they made by students?MALE PROFESSOR:Oh,we only use certain suppliers—wholesalers who've been selected by the store manager.FEMALE STUDENT:Do you ever sell things made by students?MALE PROFESSOR:We use preferred vendors only because,I mean…if we said yes to one student,we’d have to say yes to any student who asks.And the store's only so big!FEMALE STUDENT:Hmm,that’s too bad,'cause—um,I make these pretty ceramic bowls—I design'em myself—I'm a studio art major.Anyway,I was hoping I could sell’em here.You see,I’m taking Art202—“Marketing your Art.”And for my final project,I need to find a way to sell my own artwork.MALE PROFESSOR:Hmm…What about selling online?A lotta art and crafts are marketed that way.FEMALE STUDENT:I really don't have the computer skills,or the time to manage a Web site.MALE PROFESSOR:What about the Emporium—you know,that gift shop downtown? I’ve seen items by local artists there—FEMALE STUDENT:The Emporium buys directly from artists?MALE PROFESSOR:Well,they sell items on consignment.FEMALE STUDENT:Consignment…I think my professor mentioned that.MALE PROFESSOR:Yeah,you give them some items to sell on your behalf,and then you and the store split the purchase price.But they wouldn't pay you anything up front—if that’s what you want.And might may need to provide your own display case.FEMALE STUDENT:Oh,I already have a display case,a portable one with three shelves.But aren't there shops that would,you know,just buy stuff from me outright? 'Cause,if not enough bowls are sold,how would I recoup the cost of my materials—they’re not cheap…and neither was the case!MALE PROFESSOR:All the stores around here that sell craft items are small andindependently owned,like the Emporium.For them,selling on consignment lowers their risk;they don’t get stuck with unsold items—they can return them to the owner. You just have to make sure you set a retail price high enough to make it worth your while.But you're right,consignment isn't for everyone.What about the spring craft fair?You know,that outdoor market that’s held on Saturdays?Plenty of local people sell their stuff there—ceramics,jewelry,decorative items…The vendor fee is nominal,I believe.FEMALE STUDENT:Oh yeah,I remember seeing that last year…all those tables lined up in that vacant lot on Main Street,right?MALE PROFESSOR:Right!Since the craft fair's only a few blocks from campus,it seems like a good place for students to sell things.FEMALE STUDENT:Do you know how it works?MALE PROFESSOR:I think you'd just rent a space and set up a table to display your bowls on.You’d set the prices and keep all the profits.FEMALE STUDENT:Seems doable—But,hmm I don't have a car to haul everything down there.MALE PROFESSOR:You could take the campus bus—it goes into town on weekends.FEMALE STUDENT:True.But…I'd also hafta sit there all day when I should be in the library or the studio.I dunno…I suppose I could do my reading assignments between customers.题目1.Why does the woman go to talk to the man?A.To find out how the store pays artists for their workB.To purchase some ceramic coffee mugsC.To find out if the store sells objects made by studentsD.To ask about the advantages and disadvantages of consignment sales2.What is the main reason that the woman cannot display her ceramic bowls in the campus store?A.Her bowls are too expensive.B.There is not enough room for her display case.C.The store gets merchandise only from approved suppliers.D.There is little demand on campus for ceramic bowls.3.According to the conversation,what is a reason that the woman wants to sell her bowls?A.To earn enough money to buy a second display caseB.To fulfill a requirement of one of her coursesC.To impress her studio art professorD.To gain experience that could help in her future career4.What is the woman's attitude toward selling items at the Emporium?A.She is eager to display her work to the public thereB.She is encouraged because the Emporium specializes in selling ceramicsC.She is worried because she does not fully understand the consignment process.D.She is worried that she might not make much money.5.What concerns does the woman initially express about selling items at the craft fair? [Click on2answers]A.Whether doing so would interfere with her studiesB.Whether customers would appreciate her artistryC.Whether she could afford the fee charged to sellersD.Whether she would be able to transport her items to the fair答案C C BD AD译文旁白：请听一段学生和大学商店雇员之间的对话。
¡¡¡¡ÎªÁË°ïÖú´ó¼Ò¸ßЧ±¸¿¼Íи££¬Îª´ó¼Ò´øÀ´Íи£TPO52×ÛºÏд×÷ÔĶÁÔ-ÎÄ+ÌýÁ¦Ô-ÎÄ+Âú·Ö·¶ÎÄ£¬Ï£Íû¶Ô´ó¼Ò±¸¿¼ÓÐËù°ïÖú¡£¡¡¡¡Íи£TPO52×ÛºÏд×÷ÔĶÁÔ-ÎÄÎı¾£º¡¡¡¡Asteroids are large space objects made of rock and ice. There are hundreds of thousands of asteroids in our solar system. Though we often hear ideas about establishing colonies of humans to live and work on our Moon or our neighboring planet, Mars, some think that sending people to an asteroid would actually be the best colonization option for a number of reasons. Low Gravity To begin with, asteroids are often much smaller than planets, so they have lower gravity. When landing a spaceship, the craft would not be pulled as strongly or as forcefully toward the asteroid's surface, making the landing safer than landing on the Moon or Mars; it would also allow a spacecraft to carry much more equipment needed to set up the colony. It would also be easier for the spacecraft to take off again, so the spaceship would need to carry considerably less fuel for the trip back to Earth. Mining Valuable Metals Next some asteroids are rich in valuable elements and precious metals that are relatively rare on Earth, such as gold and platinum. An asteroid colony would be extremely profitable and a good source of these raw materials. The colonists or businesses sponsoring them could more than pay for the cost of their support by mining minerals and sending them back to Earth. Easy to Reach Finally, asteroids are a good option for colonization because some of them would be very easy to reach. There are a number of asteroids that periodically come within or near Earth's orbit Some of them actually get closer to Earth than our Moon. So these asteroids would be much easier and more affordable to get to and get back from than a planet like Mars, which would require a two-year trip in each direction.¡¡¡¡Íи£TPO52×ÛºÏд×÷ÌýÁ¦Ô-ÎÄÎı¾£º¡¡¡¡Now listen to a part of a lecture on the topic you just read about.¡¡¡¡Asteroid colonization is not a very practical idea. Each of the points in the reading has a serious downside.¡¡¡¡First, while low gravity on an asteroid would make landing and taking off relatively easy, low-gravity environments also present certain risks. In a low-gravity environment, people start losing muscle mass and their bone density becomes lower. Even astronauts who spend just a few months in spaceships, which are low-gravity environments, suffer from health problems like muscle and bone density loss. Imagine the health problems that long-term colonists would experience on asteroids.¡¡¡¡Second, the availability of valuable metals might make an asteroid colony seem like a profitable idea but that¡¯s not the whole picture. You have to consider additional factors. One thing is the costs. The costs of supporting a colony and oftransporting the metals are likely to be high and will reduce the profits. And furthermore, there¡¯s no guarantee that the price for which you can sell the metals will remain the same. If precious metals are mined in large quantities, it would increase the supply of the metals, which could end up lower in the market price. So mining on asteroids may not be very profitable.¡¡¡¡Third, even if some asteroids are easy to reach, they may not be easy to return from. Asteroid orbits, the path on which asteroids travel through space, can be unusual. Some orbital paths come close to earth but then move away from earth, often a great distance away from earth. So even if an asteroid gets close to earth at one point, making it easy for colonists to get to the asteroid, it does not stay close to earth. It can actually travel much farther away from earth than a planet like Mars. Getting back from an asteroid that travels that far would be a challenge.¡¡¡¡Íи£TPO52×ÛºÏд×÷Âú·Ö·¶ÎÄ£º¡¡¡¡In the reading, the article comes up with an assumption that sending people to an asteroid would be the best colonization option and lists out three reasons to support this statement. However, in the listening, the professor questions the feasibility of this plan and offers his own perspective on the issue. First, the reading states that the low-gravity environment on asteroids makes it convenient for people to colonize there. However, in the listening, the professor presents certain risks of low-gravity environments and points out the problem is not that simple. People who live in a low-gravity environment would suffer from muscle loss and lower bone density. Even those astronauts who just spend a short period of time in spaceship would also have muscle and bone density loss, not to mention stay in a low-environment asteroid for longer periods. Second, the reading claims that the abundant resources on asteroids, such as gold and platinum, would make the prospect of the colonization very profitable and is worth colonizing. However, in the listening, the professor also points out one potential problem in it. The costs of mining and transporting these materials back to earth would be so high that the profit could be quite minimal. Also, if these raw materials are excavated in large quantities, the price of them is likely to be low in the market because there are too many of them. In this case, the whole business is not lucrative at all. Third, an easy reach to an asteroid is the third reason why it is worthy of colonization. In the listening, the professor points out one exception which will make the whole issue more complicated than it was expected. Asteroids are easy to reach but not that easy to return from. When an asteroid comes near to the Earth, it is indeed convenient to get onto it. But some orbital paths of asteroids are not predictable, they could get quite far away from the Earth. Under this circumstance, getting back from there would be a challenge, or even an illusion. Therefore, in the listening, the professor asserts that the asteroid colonization is not as simple as it was expected by pointing out three potential problems in the plan.。
TPO-52-C-11.What do the speakers mainly discuss?A. Methods that the professor uses to challenge her studentsB. Reasons that the student turned in his paper a week lateC. The two parts of an assignment for a writing classD. Seldom discussed aspects of a famous poet's work2.What reason does the professor give for wanting to meet with the student?A. She wants to compliment him on the work he has done so far.B. She is concerned that the student is not reading a wide enough variety of poetry.C. She wants to lend him a book of poetry.D. She routinely meets individually with her students.3.What does the student like about Pablo Neruda's poems in the book Elemental Odes?A. That Neruda challenged himself by limiting the theme of all the poems to fruits and vegetablesB. That the poems have been written in many different stylesC. How Neruda focuses on color to make his poems more memorableD. How Neruda describes common objects in unexpected ways4.Why does the student mention the meter called iambic pentameter?A. To point out that his poem is longer than The LemonB. To explain how he approached the composition of his poemC. To explain what he liked most about Neruda's poem The LemonD. To distinguish Neruda's poetry from that of other poets5.What does the professor mean when she says this:A. Neruda was an extraordinary writer.B. Neruda should not have won a Nobel Prize.C. It is surprising that Neruda’s poems are not more popular.D. It is unfortunate that Neruda did not win a Nobel Prize.Answers：C/D/D/B/AExplication of Pablo Neruda’s PoemListen to a conversation between a student and his creative writing professor.Professor: John, listen. I can clearly see that you put a lot of time into your response paper.John: I did! It took me forever. I rewrote it a dozen times.Professor: And your hard work shows. Unfortunately, it’s a week late.John: I know. Sorry. I just got a little behind, you know, sports and homework. But I’m on top of things now.Professor: Glad to hear it! Now, as for our meeting today, I’d like to talk to all of my creative writing students one on one at least once during the term and see how they’re doing.John: I think I’m doing OK. Busy, you know, but other than that…Professor: Well, I found through the years that some of my assignments can be pretty tough for first year students like yourself, like the response paper you just did, the explication of a Pablo Nerudapoem. Emm…by the way, why did you choose "The Lemon"?It’s an unusual choice.John: It was my favorite in the book of Neruda’s poems. All the poems are about everyday objects and, you know, simple pleasures.Professor: Right, Elemental Odes, one of my favorites.John: I like how Neruda took things like fruit and vegetables and socks, and use metaphors and similes to describe them as these wonderful mysterious things, like in“The Lemon". He describes a lemon falling to Earth from the stars, and he compares a slice of lemon to a stained glass window. It’s so original!Professor: Beautiful images, aren’t they?Neruda didn’t win the Nobel Prize for literature by accident. John: No, he didn’t.Professor: Now, as you know, the paper was only the first half of the assignment, and I’m concerned about your ability to complete the second part on time, considering how much time the first part took you.John: Actually, I finished it just before I came here.Professor: Excellent!John: It was tricky, too. You know, having to write a poem inspired by "The Lemon", but in a completely different style.Professor: Right!John: In order to do that, I really had to study Neruda’s style and read a lot of his stuff, which was great, but "The Lemon" is free verse. So to do the assignment, I decided to use a strict meter - iambic pentameter, to be as different as possible.Professor: So each line of your poem has ten syllables and every other syllable is stressed. Interesting choice! Iambic pentameter is certainly different from free verse.John: It was hard for me though, because usually when I write a poem, I choose my own topic, and I just write. I don’t worry about counting syllables or anything.So, I’m kind of hoping we won’t have more assignments like this?Professor: Sorry to disappoint you, but these assignments are designed to get you out of your comfort zone, to get you reading and writing a wide variety of poetic styles.。
托福TPO52综合写作题目及范文（附解析）托福TPO52综合写作题目及范文(附解析)TPO52综合写作的阅读要点内容为蔗糖可能带来许多健康风险，当作为糖的替代品。
今天给大家带来写作思路解析及范文，希望对大家有帮助。
托福TPO52综合写作题目听力文本：M: Now listen to part of a lecture on the topic you just read about:M: Many studies have found sucralose to be perfectly safe for people to consume. And it is useful for people who are trying to lose weight. The reading’s arguments against using sucralose can all be challenged.First, about sucralose affecting the thymus. If you look closely at the studies of sucralose consumption, there were no effects on the rats at all until they were eating extremely large quantities of sucralose. In order for a human to eat the equivalent amounts that affected the rats being studied, a human would have to consume about 4000 packets of sucralose per day for a month.Second, sure, some organochlorines are toxic. If they are consumed, they are digested and stored in fat tissue, and they continue to build up in the fat tissues till they reach toxic levels. But studies show sucralose is a bit different from the other organochlorines. Sucralose is not absorbed by the digestive system very well and so it does not accumulate in the body’s fat tissue. Since sucralose is not absorbed well by the digestive system and doesn’t build up to dangerous leve ls in fat tissue, it is unlikely to have the toxic effect that the otherorganochlorines do.Finally, there is the argument that many people who use artificial sweeteners in their drinks end up eating lots of real sugar in food like cake, and so they negate the benefits of using the sweetener. Well, that argument may hold true for many artificial sweeteners but sucralose has a unique property that makes it different. Most artificial sweeteners breakdown if they are heated too much, but sucralose does not break down when heated. That means that unlike other sweeteners, sucralose can be used to bake things, like cakes and cookies, for example. People craving something sweet can turn to cakes or cookies baked with sucralose, which helps them keep their diets on track.M: Summarize the points made in the lecture, being sure to explain how they challenge the specific points made in the reading passage.阅读文本：ReadingSucralose is an artificial sweetener that is used in place of natural sugar. Many people use sucralose as a substitute for sugar to control their weight. However, there may be several health risks associated with sucralose. Also, it is not clear whether sucralose actually helps people lose weight.First, researchers in Australia did studies on rats and discovered that sucralose consumption caused shrinking of the thymus in rats. The thymus is an organ that is crucial to maintaining a healthy immune system; in humans it is particularly active in childhood. If sucralose has similar effects on humans, then long-term use of sucralose could cause harm to the immune system, especially in children.Second, sucralose is created by replacing some of the atoms in natural sugar molecules with chlorine. This means sucralose belongs to a group of chemicals called organochlorines, which is another cause for concern. Organochlorines are known to be toxic to plants and animals, including humans. Some organochlorines are even used as pesticides. Sucralose is chemically similar to these toxic chemicals, so there may be a risk of poisoning if sucralose builds up in human body tissue (in fat tissue, for example).Third, substituting artificial sweeteners for real sugar in coffee, tea, and soft drinks often does not help people lose weight, since it reinforces the habit of enjoying sweet food. When people use artificial sweeteners in their drinks, their appetite for sugar remains strong, and they satisfy their sweetness cravings by eating greater portions of foods containing real sugar, such as cakes or cookies. Such eating habits can prevent them from achieving their goal of losing weight.Summarize the points made in the lecture, being sure to explain how theysupport/contradict specific points made in the reading passage.答题思路：1. 阅读要点概括：Main point: Sucralose may bring about many health risks when used as a substitute for sugar.Sub point 1: Sucralose may cause harm to the immune system.Sub point 2: There may be a risk of poisoning if sucralose builds up in human body tissue.Sub point 3: Substituting artificial sweeteners for real sugar does not help people lose weight.2. 听力要点概括：Main point: Sucralose is perfectly safe for people to consume.Sub point 1: It requires a consumption of extremely large quantities of sucralose to affect the thymus.Sub point 2: Sucralose does not accumulate in the body’s fat tissue so that it is unlikely to have the toxic effect.Sub point 3: People can use sucralose to replace sweet while keep their diets on track.范文：The sp eaker rebuts the reading’s arguments by debunking the exaggerated tested side effect on the human body, the hasty generalization that sucralose is proven toxic, and unwarranted claims that Sucralose can increase one’s sugar intake.The speaker begins by stating that Sucralose does affect the thymus, but only when the individual consumes a very large quantity of it, over 4000 packets per day. Despite the claim from the reading that sucralose might exert similar detrimental effects on a human thymus given the conclusive side effect has been witnessed in rats, the professor argues Sucralose can only pose a threat to one’s health under mass usage.Contrary to the belief in the passage that it belongs to a group of toxic chemicals called Organochlorines, Sucralose has been shown to act differently than traditional Organochlorines. The professor argues that people have a hard time fully digesting it and it does not build up in the body, therefore it is much less toxic. This directly challenges the fundamental theory in reading.Lastly, the professor casts doubt on the validity of the assumption that sucralose can encourage binge intakes of sweet food. The reading reasons that sucralose can build a growing reliance on sweetness, thus further d amaging one’s health.However, the speaker maintains that the very nature of Sucralose can endure a high heating temperature, thus serving as a perfect candidate to replace artificial sweeteners. In that sense any unfair concern over Sucralose being a gateway sugar inducer would be groundless.。
TPO-52-L41.What is the main purpose of the lecture?A. To familiarize students with the Mayan civilization in the Classic PeriodB. To prepare students for an archaeology project about the Mayan civilizationC. To provide evidence for a point made in a previous class about the Mayan civilizationD. To call into question a common view about the decline of ancient Mayan civilization2.Why does the professor discuss Lamanai in detail?A.To present findings about one Mayan settlement from the Postclassic periodB.To describe the physical layout of the first Mayan settlements in Central AmericaC.To criticize the excavation methods used there during the 1970sD.To note how the size of a typical Mayan settlement varied throughout its history3.What is one of the features that gives Lamanai special archaeological significance?A.It was the first Mayan site in Belize to be excavated in modern times.B.It was occupied by two distinct cultural groups during the Classic period.C.It was continuously occupied by the Maya longer than any other site.D.It had an economic structure that was distinct from that of other Mayan cities.4.Why does the professor say that it would require “lots of funding” to uncover the stone structures that she discusses?A.Because there are so many of themB.Because very few archaeologists are given access to themC.Because they are located on so many different islandsD.Because of difficult weather conditions in the region5.According to the professor, what can be inferred from the ceramic artifacts found on the island?A.The island was the source of most of the pottery used at Lamanai.B.Much of Lamanai’s population relocated to the island during the Postclassic period.C.The Mayan trading network remained strong during the Postclassic period.D.The Maya developed new technological capabilities on the island.6.Why does the student say this:A.To request that the professor repeat the point she just madeB.To express his doubt about the period of time being discussedC.To disagree with the professor’s interpretation of the evidence about LamanaiD.To find out if he correctly understands the professor’s pointAnswers：D/A/C/A/C/DMaya CivilizationListen to part of a lecture in an archeology class. The professor has been discussing ancient Mayan civilization.Professor: Now, as you remember from your reading, the Maya were an ancient civilization which occupied in area corresponding to parts of modern-day Mexico and Central America. Early Mayan settlements date back over 3,000 years and say from about 600 to 900 C.E. The civilization was in what’s considered a golden age of cultural achievement, what we call the Classic period.The period after this, after the Classic Period, is called the Postclassic period. Now it’s long been thought that during the PostClassic period, Mayan civilization was in decline. But we’re continuing to find new evidence that in certain areas Mayan civilization flourished right up to the end of the Postclassic period, what we refer to as the late Postclassic period. The late Postclassic corresponds to the period from the 1200s to 1500s, right until the arrival of the Spanish in the mid-1500s. A good example of a site which continued to flourish through the late Postclassic is the inland Mayan community of Lamanai, located in what is today the country of Belize in Central America. Now, Lamanai is one of the largest and most prominent archeological sites in Belize. It was occupied for over 3000 years. That makes it the longest continually-occupied site by the ancient Maya. Large-scale excavation at Lamanai began back in 1974 under the leadership of a Canadian archeologist. The first excavation there was on a building that dated back to the late Postclassic period. When the excavation began, we didn’t know much about Mayan life during that time. As I said, most people considered the Postclassic period as a time of decline that came after the so-called golden era. But during the first few years of excavation, the archeological team realized that Lamanai had continued to be an important center of classic Mayan culture, almost right up until the 1500s.Student: So basically, what you are saying is while other Mayan cities were collapsing or had already collapsed, Lamanai was one of those places that was flourishing?Professor: Uh huh…exactly! In fact, the evidence shows that one of the greatest periods of construction in the city occurred du ring the Postclassic.That’s definitely not what was happening at neighboring sites during that time. And consider this, archeologists found ceramic artifacts from Lamanai’s late Postclassic period at a recently-discovered site on an island off the coast of Belize. And in Lamanai they found objects that had been imported from parts of the region which correspond to modern-day Mexico during the late Postclassic. What did those finds tell us?Female student: eh…the trade was still going on? So you probably still find the same Mayan social structure and economic practices, right?Professor: Yes. Now, these researchers and subsequent research teams have been helping us see a bigger picture. We now know that there was still a widespread trading network up and down a long portion of the coast of what is modern-day Mexico and Central America for more than two centuries after the golden era ended. Those finds are telling.Female student: How big is Lamanai overall?Professor: Well, in all, 700 stone structures have been documented. It takes several life times and lots of funding to uncover all of them. Ok, if that’s not a helpful mental picture…all right here’s another detail that might help. There was once a population between 35 and 55 thousand there. The southernmost end of Lamanai had become the city center by the Postclassic period. It was there at the southern end that people continued to develop technological capabilities, especially in ceramics and eventually in metal work. The center of Lamanai society had previously been in the northern part of the city. We’re not yet sure why the focus of life shifted southward only that it did.Female student: Was the former center, the one in the north smaller than the new one in the south? Like maybe the population grew so they needed more room and moved?Professor: Actually, the new city center was smaller. It’s possible that’s because the population had decreased by that point so they actually needed less room. In any case, the restructured community thrived.。
2021年托福阅读PASSAGE 52试题及答案PASSAGE 52In the early 1800's, over 80 percent of the United States labor force was engaged in agriculture.Sophisticated technology and machinery were virtually nonexistent. People who lived in the cities and were not directly involved in trade often participated in small cottage industries making handcrafted goods. Others cured meats, ran bakeries, or otherwise produced needed goods and commodities. Blacksmiths, silversmiths, candle makers, and other artisans worked in their homes or barns, relying on help of family members or apprentices.Perhaps no single phenomenon brought more widespread and lasting change to the United States society than the rise of industrialization. Industrial growth hinged on several economic factors. First, industry requires an abundance of natural resources, especially coal, iron ore, water, petroleum, and timber — all readily available on the North American continent. Second, factories demand a large labor supply. Between the 1870's and the First World War (1914-1918), approximately 23 million immigrants streamed to the United States, settled in cities, and went to work in factories and mines. They also helped build the vast network of canals and railroads that crisscrossed the continent and linked important trade centers essential to industrial growth.Factories also offered a reprieve from the backbreaking work and financial unpredictability associated with farming. Many adults, poor and disillusioned with farm life, were lured to the cities by promises of steady employment, regular paychecks, increased access to goods and services, and expanded social opportunities. Others were pushed there when new technologies made their labor cheap or expendable; inventions such as steel plows and mechanized harvesters allowed one farmhand to perform work that previously had required several, thus making farming capital-intensive rather than labor-intensive.The United States economy underwent a massive transition and the nature of work was permanently altered. Whereas cottage industries relied on a few highly skilled craft workers who slowly and carefully converted raw materials into finished products from start to finish, factories relied on specialization. While factory work was less creative and more monotonous, it was also more efficient and allowed mass production of goods at less expense.1. What aspect of life in the United States does the passage mainly discuss?(A) The transition from an agricultural to an industrial economy(B) The inventions that transformed life in the nineteenth century(C) The problems associated with the earliest factories(D) The difficulty of farm life in the nineteenth century2. Blacksmiths, silversmiths, and candle makers are mentioned in lines 5-6 as examples of artisans who(A) maintained their businesses at home(B) were eventually able to use sophisticated technology(C) produced unusual goods and commodities(D) would employ only family members3. The phrase "hinged on" in line 9 is closest in meaning to(A) recovered from(B) depended on(C) started on(D) contributed to4. Which of the following is mentioned in the passage as a reason for the industrial growth that occurred in the United States before 1914?(A) The availability of natural resources found only in the United States(B) The decrease in number of farms resulting from technological advances(C) The replacement of canals and railroads by other forms of transportation(D) The availability of a large immigrant work force5. The word "lured" in line 19 is closest in meaning to(A) attracted(B) assigned(C) restricted(D) attached6. The word "Others" in line 20 refers to other(A) adults(B) promises(C) goods and services(D) social opportunities7. The word "expendable" in line 21 is closest in meaning to(A) nonproductive(B) unacceptable(C) nonessential(D) unprofitable8. It can be inferred from the passage that industrialization affected farming in that industrialization(A) increased the price of farm products(B) limited the need for new farm machinery(C) created new and interesting jobs on farms(D) reduced the number of people willing to do farm work9. What does the author mean when stating that certain inventions made farming "capital-intensive rather than labor-intensive" (lines 23-24)?(A) Workers had to be trained to operate the new machines.(B) Mechanized farming required more capital and fewer laborers.(C) The new inventions were not helpful for all farming activities.(D) Human labor could still accomplish as much work as the first machines.10. According to the passage , factory workers differed from craft workers in that factory workers(A) were required to be more creative(B) worked extensively with raw materials(C) changed jobs frequently(D) specialized in one aspect of the finished product onlyANSWER KEYSPASSAGE 52 AABDA ADDBD。
tpo52三篇托福阅读TOEFL原文译文题目答案译文背景知识阅读-1 (2)原文 (2)译文 (5)题目 (7)答案 (14)背景知识 (18)阅读-2 (23)原文 (23)译文 (26)题目 (28)答案 (37)背景知识 (40)阅读-3 (42)原文 (42)译文 (45)题目 (48)答案 (56)背景知识 (60)阅读-1原文Stream Deposit①A large,swift stream or river can carry all sizes of particles,from clay to boulders.When the current slows down,its competence(how much it can carry)decreases and the stream deposits the largest particles in the streambed.If current velocity continues to decrease-as a flood wanes,for example-finer particles settle out on top of the large ones. Thus,a stream sorts its sediment according to size.A waning flood might deposit a layer of gravel,overlain by sand and finally topped by silt and clay.Streams also sort sediment in the downstream direction. Many mountain streams are choked with boulders and cobbles,but far downstream,their deltas are composed mainly of fine silt and clay. This downstream sorting is curious because stream velocity generally increases in the downstream petence increases with velocity,so a river should be able to transport larger particles than its tributaries carry.One explanation for downstream sorting is that abrasion wears away the boulders and cobbles to sand and silt as the sediment moves downstream over the years.Thus,only the fine sediment reaches the lower parts of most rivers.②A stream deposits its sediment in three environments:Alluvial fans and deltas form where stream gradient(angle of incline)suddenly decreases as a stream enters a flat plain,a lake,or the sea;floodplain deposits accumulate on a floodplain adjacent to the stream channel; and channel deposits form in the stream channel itself.Bars,which are elongated mounds of sediment,are transient features that form in the stream channel and on the banks.They commonly form in one year and erode the next.Rivers used for commercial navigation must be recharged frequently because bars shift from year to year.Imagine a winding stream.The water on the outside of the curve moves faster than the water on the inside.The stream erodes its outside bank because the current's inertia drives it into the outside bank.At the same time,the slower water on the inside point of the bend deposits sediment,forming a point bar.A mid-channel bar is a sandy and gravelly deposit that forms in the middle of a stream channel.③Most streams flow in a single channel.In contrast,a braided stream flows in many shallow,interconnecting channels.A braided stream forms where more sediment is supplied to a stream than it can carry. The stream dumps the excess sediment,forming mid-channel bars.The bars gradually fill a channel,forcing the stream to overflow its banks and erode new channels.As a result,a braided stream flows simultaneously in several channels and shifts back and forth across itsfloodplain.Braided streams are common in both deserts and glacial environments because both produce abundant sediment.A desert yields large amounts of sediment because it has little or no vegetation to prevent erosion.Glaciers grind bedrock into fine sediment,which is carried by streams flowing from the melting ice.If a steep mountain stream flows onto a flat plain,its gradient and velocity decrease sharply.As a result,it deposits most of its sediment in a fan-shaped mound called an alluvial fan.Alluvial fans are common in many arid and semiarid mountainous regions.④A stream also slows abruptly where it enters the still water of a lake or ocean.The sediment settles out to form a nearly flat landform called a delta.Part of the delta lies above water level,and the remainder lies slightly below water level.Deltas are commonly fan-shaped, resembling the Greek letter"delta"(∆).Both deltas and alluvial fans change rapidly.Sediment fills channels(waterways),which are then abandoned while new channels develop as in a braided stream.As a result,a stream feeding a delta or fan splits into many channels called distributaries.A large delta may spread out in this manner until it covers thousands of square kilometers.Most fans,however,are much smaller,covering a fraction of a square kilometer to a few square kilometers.The Mississippi River has flowed through seven different delta channels during the past5,000to6,000years.But in recent years,engineers have built great systems of levees(retaining walls)in attempts to stabilize the channels.译文溪流沉积物①一条大而湍急的小溪或河流可以承载各种大小的颗粒，从微小的粘土到巨石。
