托福TPO52 三篇阅读翻译!!倒序!!
托福阅读tpo52R-3原文+译文+题目+答案+背景知识
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。
托福听力52-L2-Interactions within an Ecosystem
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tpo52 section2 对话讲座原文+题目+答案+译文
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。
托福TPO52综合写作阅读原文+听力原文+满分范文
¡¡¡¡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.。
托福听力52-C1-explication of pablo neruda's poem
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）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.。
托福TPO52口语Task4阅读文本+听力文本+题目+满分范文
Explain the concept of impression management, using the examples provided by the professor.
托福 TPO52 口语 Task4 满分范文：
In the reading, the article talks about impression management, which means the
way we manage or control our impressions that we make on others. In the listening, the professor gives out two examples to illustrate this title. First, when a student is going to give a presentation to the whole class, he may dress up a little bit more formally than usual. In this way, he could make others aware that he takes this presentation very seriously, that he’s come prepared and that he wants to present to them a high-quality presentation. Another example is that once when the professor gave the president of the university a ride to a meeting across town, he had taken the trash out of his back seat and even had his car washed the day before he gave the president a ride. When the president got into his car, he turned the radio to the classical music station which seemed more sophisticated. The reason why he did all these things was that he wanted to make a good impression on the president. Therefore, by giving out these two examples, the professor explains what is meant by impression management.
托福听力52-L4-Maya civilization
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.。
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关于为什么纳图夫人与他们的祖先有着这样或那样的不同，以及他们为什么身先士卒将农耕作为一种生活方式，至今仍然是个谜。当然，天气变化是一个原因，越来越严重的干旱以及人口密度的增长可能迫使他们加强对谷物的开发利用，这转而可能会促进镰刀、其他工具以及使农业变得高效化的永久群落的发展。但是人们还不清楚这些因素具体是什么时候与其他起作用的因素发生相互影响的。
在不知情者的眼中，清除林地和燃烧林地的过程看似是随意的，但事实并非如此。
来种植谷类。除了在耕种条件较好的地区，比如经常被水淹没的河漫滩地区：热带非洲的土壤的肥力只在中等水平甚至肥力很低。农业的艺术就在于小心地选择土地，那就是说，知道哪些土壤是轻土壤，容易耕种，很容易用小锄头翻种，并且可以在经过几年的耕种之后，仍然保持它的肥力，因为谷类植物会迅速地消耗氮和土壤中其他的养分。一旦谷类植物被种植，刀耕火种的农业会迅速扩大其范围，就如同在新土地上出现一个又一个的村落一样，轮耕农业会迅速地发展，以至于一个专家估计它仅仅只用了两个世纪的时间，就覆盖了从非洲东部到南部2000公里范围的土地。
和其他地方的情况一样，在非洲，牛是饲养起来很费劲的动物。如果要饲养各种规模的牛群的话，这些牛至少每24小时就需要喝一次水，而且需要大片的牧场。饲养的秘诀在于仔细挑选放牧场地，尤其是在季节性降雨会导致全年牧草质量有明显差异的环境中。即使是规模适中的牛群也需要大片的土地和相当大的可移动性。为了获得这样的土地，经常需要牛群移动相当远的距离，甚至是从夏季牧场移动到冬季牧场。同时，放牧人不得不让牲畜在有舌蝇出没的地带吃草。唯一能够保护人类和牲畜，不患上昏睡病（一种由舌蝇传播的疾病）的办法，就是避免在这些地区定居或者放牧——对非洲东部和中部地区的牧民来说，这个办法严重地限制了他们的迁移。结果是，小牛群迅速地向南部地区迁移，在那里人们可以放牧。在谷类农业占领最南部的撒哈拉沙漠之前，非洲东部和南部稀树草原地区的一些依靠狩猎和采集生活的人可能已经饲养了牛群和其他家养动物，他们将牲畜作为礼物交换，或者通过劫掠放牧的邻居，来获得这些牲畜。
和主流观点相反：没有所谓的“纯粹”的牧民，即只依靠牧群生存的社会。撒哈拉沙漠地区为了躲避干旱而向南迁移的牧民，几乎肯定的是他们也在种植高粱、小米和其他热带降雨作物。到公元前1500年，谷类作物已经广泛分布于整个撒哈拉沙漠南部的稀树草原带。小型农业社区遍布在草原和西非东部森林的边界处，这些小型农业社区都依赖于所谓的轮耕法。这种形式的农业包括清理林地，焚烧清理过的地块上的那些被砍倒的灌木丛，将灰烬混合在土壤中，然后在这些制备好的土地上耕种。几年后，土地耗尽了养分，于是农民们继续前进，开辟新的林地，让原来的荒地休耕。轮耕法，也被称为“刀耕火种”，高度适用于没有犁的稀树草原地区的农民，因为这种方法能够消耗最少的能量。
1.Stream Deposit
一条大而湍急的溪流或河流可以携带各种大小的颗粒，小到粘土，大到巨石。当水流放缓的时候，其携带能力（能够携带的颗粒量）会减弱，最大的颗粒会沉淀在河床上。如果水流的速度继续减弱——比如洪水消退时——更细的颗粒会沉淀在大颗粒上。因此，溪流按大小将沉积物分类。洪水消退时最先可能会沉积一层砾石，接着沙子会覆盖在砾石之上，最后淤泥和黏土会覆盖在最上面。河流也会沿着下游的方向将沉淀物分类。许多山间的溪流会被巨砾和鹅卵石阻塞，但在更远处的下游，三角洲主要是由细泥和黏土堆积成的。这种顺流而下的分类是很奇妙的，因为河流的速度通常在下游方向加快。水流的携带能力随着流速的加快而提升，因此一条河流可以输送的颗粒应该比它的支流所携带的颗粒更大。对这种顺流而下分类的一种解释是，随着沉淀物年复一年地向下游移动，水流的摩擦力将巨砾和卵石磨成了沙子和淤泥。因此，只有细泥沙能到达大多数河流的下游。
想象一条蜿蜒的河流。河流会对其外围的河岸造成侵蚀，因为水流的惯性驱使河流冲向河岸。与此同时，河流内部较缓的水流会沉淀砂石，形成一个点坝。河心沙洲是在河道中央形成的，由沙子和碎石组成的沉积物。
大多数河流是单河道。相反，辫状河由很多浅的、互相连接的河道组成。当河流携带更多的泥沙，泥沙量超出河流的携带能力的时候，这些地方就会形成辫状河。河流会卸下多余的泥沙，形成河心沙洲。沙洲会渐渐填满河道，迫使水流溢出堤岸，侵蚀出新的河道。其结果是，辫状河在多个河道同时流动，并在河漫滩上来回流动。辫状河在沙漠和冰川环境中都很常见，因为沙漠和冰川都能产生大量的沉淀物。沙漠能产生大量沉积物，因为它几乎没有或者根本没有植被来防止其被侵蚀。冰川将基岩研磨成细小的沉积物，这些沉淀物会被冰川融化后形成的水流所携带。如果一条陡峭的山溪流到平坦的平原上，它的坡度和速度就会急剧下降。结果，它会把大部分的泥沙沉淀下来，形成一个扇形土丘，被称为冲积扇。冲积扇在许多干旱、半干旱的山区很常见。
3.Early Food Production in Sub-Saharan Africa
在更新世末期（大约公元前10000年），食品生产的技术可能已经在非洲西部和中部的热带雨林的边缘地区使用，在那里非洲山药等根茎型植物的普遍使用，使人们认识到自己种植食物的好处。这种原始形式的“蔬菜栽培”（块根植物和树本作物的种植）可能已经成为了一种经济传统，基于这种传统，夏季降水谷类作物的种植也采用嫁接的办法，这种种植技术已经在撒哈拉沙漠南部边界地区的草原南部被使用。随着撒哈拉沙漠在公元前5000年之后干涸，游牧民族（牧民）向南沿着主要河道迁移到了西非和苏丹的热带草原地带。
纳图夫人有着和他们祖先不同的聚居模式。他们的一些营地要比以前的任何营地都大得多（超过1000平方米），而且他们有可能在一些营地块搭建了地基和其他建筑构件。贝壳、黑曜石以及其他商品的贸易在不断增长，人类学家们猜测易腐食品的交换（例如兽皮和食物）以及盐的交换也在不断增长。随着野生谷物在日常饮食中的重要性日益增加，食盐可能第一次几乎成为一种必需品：吃很多肉的人可以从肉类中获取必要的盐分，但是以谷物为食的可能会导致盐分的缺乏。在早期的村庄里，盐可能是一种重要的食品防腐剂。
一条河流会在三种环境下发生沉淀：在河流进入平原、湖泊或大海的时候，河流坡度（倾斜的角度）会突然下降，在那些地方会形成冲积扇和三角洲；河漫滩沉积物会堆积在河道附近的漫滩上；河流内部也会形成河道沉积物。砂坝，即细长条的泥沙堆积物，是河流内部和河流两岸所形成的沉淀物的瞬态特征。砂坝通常在一年内形成，下一年就会被消磨掉。用于通商航行的河道必须频繁地修整，因为砂坝每年都会变。
2.Natufian Culture
在大约12500年到10200年之前，纳图夫文明时期的考古记录中，我们可以看到农业起源的明确证据，纳图夫位于中东的一个被称为累范特的地区——大约在地中海东部，阿拉伯半岛的北部
纳图夫人的石器包含许多镰刀状的刀片，这些刀片显示出了收割谷物的磨耗特征。
同时，手推石磨和其他被用来加工谷物的石器在纳图夫遗址中大量出现，并且很多这样的石器都显示出了长期、集约利用的痕迹。和镰状刀片一起出现的还有很多研磨石，它们主要是石灰石或玄武岩制成的研钵和杵。也有证据表明，这些沉重的研磨石是从很远的地方运过来的，某些情况下运输距离可能超过30公里，这不是目前已知的早期人类能做到的事情。用于使渔网下沉的鱼钩和砝码证明鱼类在一些地区的饮食结构中变得越来越重要。石头容器表明了人们对容器需求的增加，但是没有证据表明纳图夫人用黏土或陶土制作器皿。对纳图夫人牙齿的研究也强有力地表明这些人专门收集谷物并且可能会种植谷物，或正处于驯化作物的过程中，但是纳图夫人也仍然是狩猎者，他们会在一些植被更繁茂的地区集中猎杀羚羊和鹿，在较为干旱的地区猎杀野山羊和马。
当河流汇入湖泊或海洋中的静水时，水流速度也会骤然减慢。泥沙会沉淀下来，形成一个近乎平坦的地貌，被称为三角洲。三角洲的一部分在水面之上，而剩余的部分略微低于水面。三角洲通常为扇形，形状和希腊字母“∆”很类似。三角洲和冲积扇都变化得很快。沉积物会填满河道（水道），然后这些河道就会被废弃，而新的河道就会像辫状河那样形成。结果是，一条形成三角洲或冲积扇的河流会分裂成多条河流，这些河流被称为支流。一个大三角洲可能会以这种方式延展开，直到占地数千平方公里。然而，大多数冲积扇，规模要小得多，覆盖一平方公里至几平方公里的小片土地。过去的5000到6000年内，密西西比河流经之处，已经形成了7个三角洲。但是近年来，工程师们建造了堤坝（挡土墙）系统以试图加固河道。
一如既往地，一个重大的文化变革不仅仅是由简单的经济的变化所造成的。纳图夫人用很多材料制作了（可能穿戴了）小珠子和垂饰，包括宝石和海里的贝壳，这些材料都需要进口才能获得，可能这些装饰品事实上反映了民族认同感的增强，或者反映了身份和族群地位上的一些不同。巧妙雕刻的动物、女人以及其他物品的塑像出现在了许多纳图夫遗址中，纳图夫时期的洞穴壁画曾在安纳托利亚、叙利亚和伊朗被发现。超过400座纳图夫人的墓葬被发现，其中大多数都是建在楼层里的简单的坟墓。据考古学家Belfer-Cohen记载，这些墓葬可能反映出了一种祖先崇拜，团队意识情感纽带的增强以及对特殊地区的一种依赖性，直到纳图夫时代后期，这里的人们才将生活区和墓葬区严格地区分开。与累范特的更新世文化相比，纳图夫文化好像经历了更大的社会变化。