托福听力｜TPO49题目+答案解析
托福听力tpo49 两篇对话精析
托福听力tpo49两篇对话精析Conversation1 (1)原文 (1)题目 (4)答案 (6)译文 (6)Conversation2 (8)原文 (8)题目 (11)答案 (13)译文 (13)Conversation1原文NARRATOR:Listen to a conversation between a student and a librarian. MALE STUDENT:Uh,hi,I need to get into Special Collections.In particular the British Literature.I was working with some of the William Blake books.FEMALE LIBRARIAN:Well,then you must know that access is restricted.MALE STUDENT:Um,I was in a seminar with Professor Gray,and she authorized access for us.FEMALE LIBRARIAN:Oh,if that's the case…let me check.Right,yeah, but it looks like that expired at the end of last semester.MALE STUDENT:But I really need to get back in there.See,I didn't quite finish my project…FEMALE LIBRARIAN:Ah ha,the plot thickens!Well,it's easy enough; have Professor Gray authorize you again.You see,these editions are rare and shouldn't be handled more than necessary.Can you work from later editions?Or microfilm?MALE STUDENT:Not really…actually my project—well,it involves some annotations in the particular edition here.They haven't been reproduced because they’re really not part of the text.generally clean them up. They’re quite hard to see…FEMALE LIBRARIAN:Well,often the characteristics of the manuscripts have been recorded.These types of extraneous markings might also be noted.MALE STUDENT:I don't think they are.They're very faint,and well,I think I have a new angle on them.There was a study once a long time ago about these notes that everybody else has since taken for granted, without checking for themselves.I think there might have been amistake in the past,that they were misread…FEMALE LIBRARIAN:So,get Professor Gray…MALE STUDENT:Uh,she's away this semester.I had to beg her to give me extra time on this project.I haven't even received a grade in the class yet.And,this class is a prerequisite for other classes in my major.I really need to see those books so I can finish up this project and get back on course to graduate on time.FEMALE LIBRARIAN:Everybody has special circumstances…MALE STUDENT:Two hours?One hour?I promise to be careful.I just need to look at a few pages with a strong magnifying glass. FEMALE LIBRARIAN:Well,I can't let you in without authorization from your professor.Can you get in touch with her somehow?MALE STUDENT:Maybe she's checking her e-mail.I really thought I'd be able to straighten this out without her.You know,she did me a huge favor by giving me the extra time.I feel like I'm skating on thin ice with her…FEMALE LIBRARIAN:You know,you were lucky to have had permission to look at the books last semester.If we don't maintain our policies,they'll disintegrate.MALE STUDENT:I know.Would an e-mail from her or a phone call begood enough?FEMALE LIBRARIAN:Of course.题目1.What are the speakers mainly discussing?A.The student's difficulties locating sources for a research projectB.The topic of the student's research projectC.The student's request to visit a particular part of the libraryD.Procedures for requesting different editions of a book2.Why is the student unable to use later editions or reproductions of a book he mentions?A.The later editions contain errors.B.Professor Gray specified the use of a particular edition.C.The later editions must be requested from another library.D.Reproductions typically omit the specific material he needs.3.Why is the student reluctant to contact Professor Gray?A.He already has disturbed her several times during her time away from campus.B.He does not feel comfortable about asking her for another favor.C.He does not know her e-mail address.D.He wants to surprise her with a completed project.4.What does the woman imply about the rules regarding Special Collections?A.The rules are unfair to the students.B.The rules are in place to protect the books.C.The rules are determined by the professors.D.The rules have changed since the previous semester.5.What does the woman mean when she says this:FEMALE LIBRARIAN:Everybody has special circumstances.A.She has been in a similar situation herself.B.She will help the student solve his problem.C.She has often heard this kind of story from students.D.She thinks the student should try to understand her situation.答案C D B B C译文旁白：接下来听一段学生和图书管理员之间的对话。
tpo48三篇阅读原文译文题目答案译文背景知识
托福阅读tpo48全套解析阅读-1 (2)原文 (2)译文 (5)题目 (7)答案 (17)背景知识 (18)阅读-2 (19)原文 (19)译文 (23)题目 (25)答案 (36)背景知识 (37)阅读-3 (38)原文 (38)译文 (41)题目 (43)答案 (53)背景知识 (57)阅读-1原文Chinese Population Growth①Increases in population have usually been accompanied(indeed facilitated)by an increase in trade.In the Western experience, commerce provided the conditions that allowed industrialization to get started,which in turn led to growth in science,technology,industry, transport,communications,social change,and the like that we group under the broad term of“development.”However,the massive increase in population that in Europe was at first attributed to industrialization starting in the eighteenth century occurred also and at the same period in China,even though there was no comparable industrialization.②It is estimated that the Chinese population by1600was close to150 million.The transition between the Ming and Qing dynasties(the seventeenth century)may have seen a decline,but from1741to1851 the annual figures rose steadily and spectacularly,perhaps beginning with143million and ending with432million.If we accept these totals, we are confronted with a situation in which the Chinese population doubled in the50years from1790to1840.If,with greater caution,we assume lower totals in the early eighteenth century and only400million in1850,we still face a startling fact:something like a doubling of the vastChinese population in the century before Western contact,foreign trade, and industrialization could have had much effect.③To explain this sudden increase we cannot point to factors constant in Chinese society but must find conditions or a combination of factors that were newly effective in this period.Among these is the almost complete internal peace maintained under Manchu rule during the eighteenth century.There was also an increase in foreign trade through Guangzhou (southern China)and some improvement of transportation within the empire.Control of disease,like the checking of smallpox by variolation may have been important.But of most critical importance was the food supply.④Confronted with a multitude of unreliable figures,economists have compared the population records with the aggregate data for cultivated land area and grain production in the six centuries since1368.Assuming that China’s population in1400was about80million,the economist Dwight Perkins concludes that its growth to700million or more in the 1960s was made possible by a steady increase in the grain supply,which evidently grew five or six times between1400and1800and rose another50percent between1800and1965.This increase of food supply was due perhaps half to the increase of cultivated area,particularly by migration and settlement in the central and western provinces,and half to greater productivity—the farmers’success in raising more crops perunit of land.⑤This technological advance took many forms:one was the continual introduction from the south of earlier-ripening varieties of rice,which made possible double-cropping(the production of two harvests per year from one field).New crops such as corn(maize)and sweet potatoes as well as peanuts and tobacco were introduced from the Americas.Corn, for instance,can be grown on the dry soil and marginal hill land of North China,where it is used for food,fuel,and fodder and provides something like one-seventh of the food energy available in the area.The sweet potato,growing in sandy soil and providing more food energy per unit of land than other crops,became the main food of the poor in much of the South China rice area.⑥Productivity in agriculture was also improved by capital investments, first of all in irrigation.From1400to1900the total of irrigated land seems to have increased almost three times.There was also a gain in farm tools,draft animals,and fertilizer,to say nothing of the population growth itself,which increased half again as fast as cultivated land area and so increased the ratio of human hands available per unit of land. Thus the rising population was fed by a more intensive agriculture, applying more labor and fertilizer to the land.译文中国的人口增长①人口增长通常伴随着（事实上促进了）贸易的增加。
托福阅读tpo49R-3原文+译文+题目+答案+背景知识
TPO49阅读-1Background for the Industrial Revolution原文 (1)译文 (2)题目 (3)答案 (8)背景知识 (8)原文Background for the Industrial Revolution①The Industrial Revolution had several roots, one of which was a commercial revolution that, beginning as far back as the sixteenth century, accompanied Europe’s expansion overseas. Both exports and imports showed spectacular growth, particularly in England and France. An increasingly larger portion of the stepped-up commercial activity was the result of trade with overseas colonies. Imports included a variety of new beverages, spices, and ship’s goods around the world and brought money flowing back. Europe’s economic institutions, particularly those in England, were strong, had wealth available for new investment, and seemed almost to be waiting for some technological breakthrough that would expand their profit-making potential even more.②The breakthrough came in Great Britain, where several economic advantages created a climate especially favorable to the encouragement of new technology. One was its geographic location at the crossroads of international trade. Internally, Britain was endowed with easily navigable natural waterway, which helped its trade and communication with the world. Beginning in the 1770’s, it enjoyed a boom in canal building, which helped make its domestic market more accessible. Because water transportation was the cheapest means of carrying goods to market, canals reduced prices and thus increased consumer demand. Great Britain also had rich deposits of coal that fed the factories springing up in industrial and consumer goods.③Another advantage was Britain’s large population of rural, agricultural wage earners, as well as cottage workers, who had the potential of being more mobile than peasants of some other countries. Eventually they found their way to the cities or mining communities and provided the human power upon which the Industrial Revolution was built. The British people were also consumers; the absence of internal tariffs, such as those that existed in France or Italy or between the German states, made Britain the largest free-trade area in Europe. Britain’s relatively stable government also helped create an atmosphere conducive to industrial progress.④Great Britain’s better-developed banking and credit system also helped speed the industrial progress, as did the fact that it was the home of an impressive array of entrepreneurs and inventors. Among them were a large number of nonconformists whose religious principles encouraged thrift and industry rather than luxurious living and who tended to pour their profits back into their business, thus providing the basis for continued expansion.⑤A precursor to the Industrial Revolution was a revolution in agricultural techniques. Ideas about agricultural reform developed first in Holland, where as early as the mid-seventeenth century, such modern methods as crop rotation, heavy fertilization, and diversification were all in use. Dutch peasant farmers were known throughout Europe for their agricultural innovations, but as British markets and opportunities grew, the English quickly learned from them. As early as the seventeenth century the Dutch were helping them drain marshes and fens where, with the help of advanced techniques, they grew new crops. By the mid-eighteenth century new agricultural methods as well as selective breeding of livestock had caught on throughout the country.⑥Much of the increased production was consumed by Great Britain’s burgeoning population. At the same time, people were moving to the city, partly because of the enclosure movement; that is, the fencing of common fields and pastures in order to provide more compact, efficient privately held agricultural parcels that would produce more goods and greater profits. In the sixteenth century enclosures were usually used for creating sheep pastures, but by the eighteenth century new farming techniques made it advantageous for large landowners to seek enclosures in order to improve agricultural production. Between 1714 and 1820 over 6 million acres of English land were enclosed. As a result, many small, independent farmers were forced to sell out simply because they could not compete. Non-landholding peasants and cottage workers, who worked for wages and grazed cows or pigs on the village common, were also hurt when the common was no longer available. It was such people who began to flock to the cities seeking employment and who found work in the factories that would transform the nation and, the world.译文工业革命的背景①工业革命有几个根源，其中之一是随着欧洲的海外扩张，早在16世纪就开始的商业革命。
托福TPO49综合写作阅读原文+听力原文+满分范文
为了帮助大家高效备考托福，为大家带来托福TPO49综合写作阅读原文+听力原文+满分范文，希望对大家备考有所帮助。
托福TPO49综合写作阅读原文文本： Like many creatures, humpback whales migrate long distances for feeding and mating purposes. How animals manage to migrate long distances is often puzzling. In the case of humpback whales, we may have found the answer: they may be navigating by the stars, much as early human sailors did. What we know about humpback whales makes this a distinct possibility. First, humpback whales seem to be intelligent enough to use stars to navigate by. Whales' brains have a high degree of complexity--a common determiner of intelligence. This suggests that the whales' brain power far exceeds that of most other animals. The whales' well-developed cognitive ability seems to provide a sound basis for the ability to use a complex, abstract system of sensory stimuli such as the night sky for orientation. Second, humpback whales migrate in straight lines. Animals can maintain movement in a straight direction for long distances only if they orient themselves by some external objects or forces. Many birds and other terrestrial creatures, for example, use physical landmarks to help them stay on track as they migrate. Whales, which swim in the open ocean, cannot rely on land features; they could, however, rely on stars at night to provide them with external signs by which to maintain direction over long distances. Third, humpback whales exhibit an unusual behavior: they are sometimes observed floating straight up for minutes at a time, their heads above the water as though they were looking upward. The behavior is known as spy-hopping, and it is very rare among marine animals. One explanation for the function of spy-hopping is that the whales are looking at the stars, which are providing them with information to navigate by. 托福TPO49综合写作听力原文文本： Professor: The theory that humpback whales use the stars to navigate the open seas is a fascinating one, but the evidence supporting the theory is not very convincing. First, there doesn’t seem to be any real connection between intelligence and an animal's ability to use stars for navigation. You know, there are other animals that use stars to navigate. Some birds have this ability, like ducks for example. Now the general cognitive ability of ducks is only average. They are not highly intelligent. The fact that the ducks evolved the ability to use stars for navigation does not seem to have much of a connection to their overall intelligence. It's just an instinct they were born with, not a sign of intelligence. So the fact that humpback whales happen to be intelligent does not make them particularly likely to use stars for navigation. The two things just don't seem to be connected. Second, there may be a different explanation for the humpback whale’s abilityto navigate in straight lines. Remember that for animals to be able to do this, they have to sense some external object or force. Well, the external force the whales could be sensing is Earth’s magnetic field. Humpback whales have a substance in their brains called biomagnetite. Generally, the presence of biomagnetite in an animal’s body makes that animal sensitive to Earth’s magnetic field. The fact that there’s biomagnetite in the brains of humpback whales suggests that they orient themselves by the magnetic field rather than the stars when they migrate.Third, spyhopping probably has nothing to do with looking at stars. Spyhopping is rare, but there are other animals that exhibit it. Some sharks do it, for example. But sharks don't migrate or look at stars. Sharks spyhop to look for animals they want to hunt. And another thing, humpback whales often spyhop during the day, when no stars can be seen. So to suggest that the function of spyhopping is to look at stars is pure speculation. 托福TPO49综合写作满分范文： In the reading passage, the author states that humpback whales may navigate by stars to migrate long distances. However, the professor refutes this idea and thinks the reasons listed in the reading are unconvincing. First of all, the author claims that humpback whales are intelligent enough to navigate by stars, while the professor states that there is no correlation between intelligence and an animal’s ability to use stars for navigation. For example, some birds such as ducks evolved the ability for navigation by stars. And ducks are only of general cognitive ability, not as advanced as humpback whales’. So, it seems that there is no real connection between intelligence and the ability to use stars for navigation. In addition, the author argues that humpback whales have no land features in the ocean to help them migrate in straight lines for long distance. So, they have to rely on stars. However, the professor challenges this statement by pointing out that the presence of biomagnetite in the brains of humpback whales enables them to be sensitive to Earth’s magnetic field. It is Earth’s magnetic field that helps humpback whales to migrate. Finally, the professor cast doubt on what is stated in the reading that humpback whales look at the stars through spy-hopping, which is a rare behavior among marine animals. He claims that there is no connection between spy-hopping and looking at stars since there are other animals exhibit this behavior but do not migrate, such as sharks. Also, humpback whales do spyhop during the day when there are no stars can be seen in the sky. So, the statement that humpback whales adopt spyhopping to look at stars is not convincing. 以上是给大家整理的托福TPO49综合写作阅读原文+听力原文+满分范文，希望对你有所帮助!。
托福阅读tpo49R-2原文+译文+题目+答案+背景知识
TPO49阅读-2 Movable Type原文 (1)译文 (2)题目 (4)答案 (8)背景知识 (8)原文Movable Type①Nothing divided the medieval world in Europe more decisively from the Early Modern period than printing with movable type. It was a German invention and the culmination of a complex process. The world of antiquity had recorded its writings mainly on papyrus. Between 200 B.C and A.D 300, this was supplemented by vellum, calf skin treated and then smoothed by pumice stone. To this in late Roman times was added parchment, similarly made from the smoothed skin of sheep or goats. In the early Middle Ages, Europe imported an industrial process from China, which turned almost any kind of fibrous material into pulp that was then spread in sheets. This was known as cloth parchment. By about 1150, the Spanish had developed the first mill for making cheap paper (a word contracted from "papyrus", which became the standard term). One of the most important phenomena of the later Middle Ages was the growing availability of cheap paper. Even in England, where technology lagged far behind, a sheet of paper, or eight octavo pages, cost only a penny by the fifteenth century.②In the years 1446-1448, two German goldsmiths, Johannes Gutenberg and Johann Fust, made use of cheap paper to introduce a critical improvement in the way written pages were reproduced. Printing from wooden blocks was the old method; what the Germans did was to invent movable type for the letterpress. It had three merits: it could be used repeatedly until worn out; it was cast in metal from a mold and so could be renewed without difficulty; and it made lettering uniform. In 1450, Gutenberg began work on his Bible, the first printed book, known as the Gutenberg. It was completed in 1455 and is a marvel. As Gutenberg, apart from getting the key idea, had to solve a lot of practical problems, including imposing paper and ink into the process and the actual printing itself, for which he adapted the screw press used by winemakers, it is amazing that his first product does not look at all rudimentary. Those who handle it are struck by its clarity and quality.③Printing was one of those technical revolutions that developed its own momentum at extraordinary speed. Europe in the fifteenth century was a place where intermediate technology - that is, workshops with skilled craftspeople - waswell established and spreading fast, especially in Germany and Italy. Such workshops were able to take on printing easily, and it thus became Europe's first true industry. The process was aided by two factors: the new demand for cheap classical texts and the translation of the Latin Bible into "modern" languages. Works of reference were also in demand. Presses sprang up in several German cities, and by 1470, Nuremberg, Germany had established itself as the center of the international publishing trade, printing books from 24 presses and distributing them at trade fairs all over western and central Europe. The old monastic scriptoria-monastery workshops where monks copied texts by hand-worked closely alongside the new presses, continuing to produce the luxury goods that movable-type printing could not yet supply. Printing, however, was primarily aimed at a cheap mass sale.④Although there was no competition between the technologies, there was rivalry between nations. The Italians made energetic and successful efforts to catch up with Germany. Their most successful scriptorium quickly imported two leading German printers to set up presses in their book-producing shop. German printers had the disadvantage of working with the complex typeface that the Italians sneeringly referred to as "Gothic" and that later became known as black letter. Outside Germany, readers found this typeface disagreeable. The Italians, on the other hand, had a clear typeface known as roman that became the type of the future.⑤Hence, although the Germans made use of the paper revolution to introduce movable type, the Italians went far to regain the initiative by their artistry. By 1500 there were printing firms in 60 German cities, but there were 150 presses in Venice alone. However, since many nations and governments wanted their own presses, the trade quickly became international. The cumulative impact of this industrial spread was spectacular. Before printing, only the very largest libraries, of which there were a dozen in Europe, had as many as 600 books. The total number of books on the entire Continent was well under 100,000. But by 1500, after only 45 years of the printed book, there were 9 million in circulation.译文活字印刷①没有什么比活字印刷更能够将欧洲的中世纪和近代早期区分开来。
TPO49阅答案解析
1. The word "crucial" in the passage is closest in meaning to【词汇题】A.InterestingB.ImportantC.EstablishedD.Understood答案：B解析：crucial:至关重要的。
a是有趣的，b是重要的，c是建立的，d是理解的。
综合选项，b最符合。
2.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?Incorrect choices change the meaning in important ways or leave out essential information.【句子简化题】A.In the last few centuries,the erosion of coastline created the Neolithic stone circle in Brittany,France,at the same time that it destroyed the medieval villages in Yorkshire,England.B.Coastlines have changed even in recent times as shown by the current locations of certain Neolithic monuments and medieval villages.C.Recent changes in the coastlines near the Neolithic stone circle of Er Lannic in Brittany,France,and the medieval villages inYorkshire,England,suggest that ancient coastlines changed in similar ways.D.Changes in coastlines can lead to the creation of islands such as Er Lannic in France or the total erosion of the cliffs as in Yorkshire in England,though no considerable changes have occurred in recent periods. 答案：B解析：提取句子主干，将括号和从句里的内容先去掉，则句子为These have changed constantly through time,even in relatively recent periods,as can be seen from the Neolithic stone circle of Er Lannic,in Brittany,France or medieval villages in east Yorkshire,England。
托福听力tpo49 section2 对话讲座原文+题目+答案+译文
托福听力tpo49section2对话讲座原文+题目+答案+译文Conversation2 (1)原文 (1)题目 (4)答案 (5)译文 (5)Lecture3 (7)原文 (7)题目 (10)答案 (12)译文 (12)Lecture4 (14)原文 (14)题目 (16)答案 (18)译文 (18)Conversation2原文NARRATOR:Listen to a conversation between a student and a professor.MALE PROFESSOR:Oh hi Melanie,how are you doing?FEMALE STUDENT:I'm good thanks.I just have some questions about this paper,for your class.Do you have a second to talk about it now?MALE PROFESSOR:Oh yes,no problem;I have about20minutes before my next class.Will that be enough time?FEMALE STUDENT:Yeah I think so.Okay so the thing is,you know,okay I'm writing my paper on the history of jazz in New York City.MALE PROFESSOR:Alright,well that's a pretty broad subject.FEMALE STUDENT:Well actually I'm focusing on a specific decade–the50s–and on and I’m only doing it on a few specific artists.MALE PROFESSOR:Oh okay–because I was going to say that seemed a bit,ah,too ambitious for a10page paper.FEMALE STUDENT:Yeah.No,it's not the subject I'm having trouble with–actually the paper is practically writing itself,I mean I’ve got a lot to say and it’s going pretty well.The thing is,I have this idea…that might make it better and I was wondering if there’s any way I could get an extension…I mean I know it’s due next week right?MALE PROFESSOR:That's right,on Monday.But I don't understand,it sounds like you’re doing so well;why do you need more time?FEMALE STUDENT:Yeah well,I could write the paper as it is and turn it in on time and it would be fine…MALE PROFESSOR:But…?FEMALE STUDENT:But I was just talking to one of my friends,whose family has lived in New York forever,and it turns out that her grandfather was actually there in the period of jazz I'm writing about–I mean he was a jazz musician and he actually,like personally knew the artists I'm writing about.MALE PROFESSOR:You're kidding!Well that’s a coincidence.FEMALE STUDENT:Yeah,I know,it's cool,right?So anyway,that's why I waswondering if I could get an extension,because I thought it would be really great if I could like,interview him,for my paper…MALE PROFESSOR:Ah.FEMALE STUDENT:But I don’t think I can meet with him until early next week,so [trailing off]…MALE PROFESSOR:Ah I see,well!It would certainly add a new dimension to your paper,wouldn’t it?Have you talked with this gentleman yet?FEMALE STUDENT:Um,no,but I talked to my friend,just,you know ran the idea past her,and she said he would probably love to do it.But,you know,he's busy until next week.MALE PROFESSOR:Okay well,yeah!I think that in this case we can definitely extend your deadline until,let’s say,Friday next week?FEMALE STUDENT:Okay that would be great.MALE PROFESSOR:But just to be fair,why don't you turn in an outline of your paper on the due date.FEMALE STUDENT:The outline...oh that's no problem.It's basically done except for the parts about the interview...MALE PROFESSOR:Oh yeah...the interview.Could you have the questions ready then too...the ones you’re planning on asking?FEMALE STUDENT:Sure,yeah I can do that,too.MALE PROFESSOR:And then I'll expect the final draft next Friday.FEMALE STUDENT:Okay great!Thanks.MALE PROFESSOR:Sure,I'm looking forward to reading it!题目1.Why does the student go to see the professor?A.To ask if she can interview him for her paperB.To ask permission to extend the length of her paperC.To ask permission to change the topic of her paperD.To ask for more time to finish her paper2.What can be inferred about the student's work on her paper so far?A.She received a lot of help on the paper from professional musicians.B.She has found enough information to complete the paper.C.She did not start working on the paper early enough.D.She is having difficulty finding sources for the paper.3.Why does the student want to interview her friend's grandfather?A.He has written articles about jazz music in New York City.B.He has recordings of the musicians discussed in the woman's paper.C.He owned a historic jazz club in New York City.D.He was a jazz musician during the1950s.4.What does the professor ask the student to do on the original due date of the paper?[Click on two answers.]A.Turn in her first draftB.Hand in an outlineC.Submit interview questionsD.Confirm that she has scheduled an interview5.Why does the student say this:Professor:All right.Well,that's a pretty broad subject.Student:Well,actually I'm focusing on a specific decade,the50s.A.To address the professor's concernB.To explain a change in her approach to her paperC.To restate the professor's pointD.To request approval of her topic答案D B D BC A译文旁白：听一段学生和教授之间的对话。
托福听力tpo49 lecture1、2、3、4 原文+题目+答案+译文
托福听力tpo49lecture1、2、3、4原文+题目+答案+译文Lecture1 (1)原文 (1)题目 (4)答案 (6)译文 (6)Lecture2 (8)原文 (8)题目 (10)答案 (12)译文 (12)Lecture3 (14)原文 (14)题目 (17)答案 (19)译文 (19)Lecture4 (21)原文 (21)题目 (23)答案 (25)译文 (25)Lecture1原文NARRATOR:Listen to part of a lecture in a geology class.MALE PROFESSOR:Alaska is fascinating to geologists because of its incrediblelandscapes.Uh,permafrost has a lot to do with this.That is,the areas where the ground—the soil—is always frozen,except for the very top layer—what we call the active layer of permafrost—which melts in the summer and refreezes again in the winter.The northern part of Alaska is covered in lakes—thousands of them—and most of these are what we call thaw lakes.T-h-a-w.Thaw lakes.I'm gonna show you a few sketches of them in a minute,so you'll have a good idea of what I'm talking about.So, how these thaw lakes are formed has to do with…OK,it starts with ice wedges.The top part of the ice wedge melts—Should I back up?Ice wedges form when water runs into cracks in the ground,the permafrost,then freezes.You ever see mud after it dries?Dried mud has cracks,because when it dries, it contracts,it shrinks.Well,in winter,permafrost behaves similarly.It shrinks in winter,because it freezes even more thoroughly then,and as it shrinks,it forms deep,deep cracks.Then in the summer,when the active layer—the top layer of the permafrost—melts,the melt water runs into those cracks in the permafrost,then freezes again—because that ground,the ground beneath the active layer,is still below freezing.So,you have wedges of ice in the permafrost.Now the ice wedges widen the original cracks in the permafrost,because water expands when it freezes.All right?OK,then in autumn,the active layer on top freezes again.Then in winter,the permafrost starts contracting again and the cracks open up even wider.So the next summer,when the active layer melts again and flows into the widened cracks…and…freezes…it makes the cracks even wider.So it’s sort of a cycle through which the cracks and the wedges grow wider and wider.So when the ice wedge reaches a certain size,its top part—in the active layer—turns into a little pond when it melts in the summer.And that's the beginning of your thaw lake.[pause]There are thousands of them in northern Alaska.One of the most fascinating things about these lakes—and this is important—is that they mostly havethe same shape.Like an elongated oval,or egg shape.And what's more,all the ovals are oriented in the same way.Here's an idea of what they look like,what the landscape looks like from an aerial view,with the lakes side by side.There's been considerable research done to try to figure out what causes them to be shaped and oriented this way.We know that the shape and orientation are caused by the way the lakes grow once they're formed,but the question is,what makes them grow this way?One theory sees winds as the cause.This region of Alaska has strong winds that blow perpendicular to the lakes.What happens is,wind blows straight into the longer side of the lakes.Now,wouldn’t that erode the lake bank in that direction?The same direction as the wind?Well…no.Actually,what happens is that the waves caused by the winds build a sorta protective layer of sediment—it's called a“protective shelf”—along the bank of the lake directly in front of them;so that bank is shielded from erosion,and the waves are diverted to the sides,to the left and to the right,and that’s why the left and the right banks start eroding.Get it?The bank straight ahead is protected,but the lake currents--the waves--erode the banks to the sides.That's the current model,um,the wind erosion model,which is generally accepted.But,there's a new theory that says that[deliberately]thaw slumping,not wind,is what shapes the thaw lakes.Thaw slumping,um…OK.Sometimes,in the summer,the temperature rises pretty quickly.So the active layer of permafrost thaws faster than the water can drain from the soil.So the sides of the thaw lakes get,like,mushy,and slump,or slide,into the lake.Then,the lake water spreads out more,and the lake gets bigger,OK?Also,in that part of Alaska,the terrain is gently sloped,so the lakes are all on an incline.Here.Now,this is an exaggeration of the angle—the hill isn't this steep—butsee how with the lake's banks,the side that is farther downhill…it's smaller,lower. This short bank thaws faster than the tall one does,so it falls into the lake—it slumps, much more and much faster than the other bank.When the short banks of many lakes slump,they move farther downhill and the lakes grow—all in the same downhill direction.This is a new theory,so it hasn't been tested much yet.In field studies,when we've looked at the banks of these thaw lakes,there's not much evidence of slumping. We'd expect to see cliff-like formations there,from the slumping,but we haven't really found many of those.题目1.What is the main purpose of the lecture?[Click on two answers.]A.To contrast how different kinds of thaw lakes growB.To explain why a new theory of thaw lakes is gaining acceptanceC.To explain how processes in permafrost lead to the formation of thaw lakesD.To describe two competing theories about the growth of thaw lakes2.The professor explains thaw lake formation as a cycle of events that occur repeatedly.Summarize this cycle,starting with the event filled in below.[Click on a sentence.Then drag it to the space where it belongs.The first one is done for you. One sentence will not be used]A.Meltwater flows into cracks in permafrostB.Ice wedges inside permafrost completely meltC.Freezing water expands cracks in permafrostD.Ice in the active layer melts as temperatures riseE.Permafrost shrinks and cracks as temperatures drop..3.What is the significance of the'protective shelf'discussed by the professor?A.It prevents the slumping of lake banks.B.It shields the lake surface from strong winds.C.It redirects the waves to lake banks that do not face the wind.D.It allows the lakes to grow in the same direction as the wind blows.4.According to the thaw slumping model,which side of a thaw lake grows fastest?A.The side where the bank is shortestB.The side least exposed to windC.The side that is at the highest elevationD.The side opposite the protective shelf5.What is the professor's opinion of the thaw slumping model?A.He thinks it was urgently needed.B.He is not convinced that it has a firm basis.C.He thinks it would be better if it were simplified.D.He does not think it is very different from the old model.6.Why does the professor say this:You ever see mud after it dries?A.He wants some information from the students.B.He thinks that the students may find an example helpful.C.He realizes that he forgot to mention an important topic.D.He wants to point out an important difference between frozen ground and dry ground.答案CD EDACB C A B B译文听一段地质学的讲座。
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得听力者得天下，托福听力对于考生来说至关重要!如何攻克托福听力，除了要多听，托福TPO听力也是托儿必刷的真题.今天，小编为托福考生们带来了托福TPO49听力，希望可以帮助广大托福考生轻松备考托福。
Conversation1
1.What are the speakers mainly discussing?
A.The student’s difficulties locating sources for a research project
B.The topic of the student’s research project
C.The student’s request to visit a particular part of the library
D.Procedures for requesting different editions of a book
答案：C
解析：学生的第一句话“I need to get into special collections,in particular the british
literature”，通过I need
to表明意图是来看图书馆中关于英国文学的书籍。
而之后的全文都在讨论学生没有教授的授权，是否能借阅这些书。
所以答案选C。
2.Why is the student unable to use later editions or reproductions of a
book he mentions?
A.The later editions contain errors.
B.Professor Gray specified the use of a particular edition.
C.The later editions must be requested from another library.
D.Reproductions typically omit the specific material he needs.
答案：D
解析：通过工作人员的题问和学生的回答，我们能定位到这道题。
考点即是师生之间的问答，而回答我们要重点记。
学生说他的project需要用到文献当中的注释，而这些注释并未在复制品中体现，都被clean
up了(clean up相当于D选项中的omit忽视)。
所以答案选D。
3.Why is the student reluctant to contact Professor Gray?
A.He already has disturbed her several times during her time away from
campus.
B.He does not feel comfortable about asking her for another favor.
C.He does not know her e-mail address.
D.He wants to surprise her with a completed project.
答案：B
解析：同上题一样，又是通过师生问答引出重要考点。
学生说：我希望自已能搞定这件事而不是让教授帮我，因为之前的extra
time已经是教授帮的一个大忙了。
而现在我觉得skating on thin ice with her。
这里的skate on thin ice with
her的表达非常重要，我们一定要理解，正如我们中文所说的如履薄冰。
试想一下，当教授已经帮了你一个忙而你却没做好的情况下，你再去请求她的第二次帮忙，这种时候是不是如履薄冰，胆战心惊，最好还是别去找她了，对不对?所以这个学生也是同样的心理，故答案选B(再求教授帮第二次忙，学生心里会不舒服)。
4.What does the woman imply about the rules regarding Special
Collections?
A.The rules are unfair to the students.
B.The rules are in place to protect the books.
C.The rules are determined by the professors.
D.The rules have changed since the previous semester.
答案：B
解析：Employee用这样的一句话“If we don't maintain our policies,they'll
disintegrate”再次拒绝了学生，这里的policies(policy政策)等同于B选项中的rules 规定。
如果我们不维持我们的规定，这些文献都会损坏。
所以这些规定就是用来保护这些文献书籍，故答案选B。
5.Replay: What does the woman mean when she says this:
A.She has been in a similar situation herself.。