[外语类试卷]大学英语四级模拟试卷141及答案与解析.doc

《[外语类试卷]大学英语四级模拟试卷141及答案与解析.doc》由会员分享，可在线阅读，更多相关《[外语类试卷]大学英语四级模拟试卷141及答案与解析.doc（47页珍藏版）》请在麦多课文档分享上搜索。

1、大学英语四级模拟试卷 141及答案与解析 一、 Part I Writing (30 minutes) 1 1. 一些学生不重视课本； 2如何最好地利用课本。 How to Make Full Use of Your Textbooks 二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions atta

2、ched to the passage. For questions 1-7, mark： Y (for YES) if the statement agrees with the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 2 Weight-Loss Nirvana? A Subst

3、ance That Makes Fat Mice Thin Just Might Work for Humans Too In the US, where one in three adults is seriously overweight, the news carried by the journal Science last week - that Friedman and his colleagues at the Howard Hughes Medical Institute and New York Citys Rockefeller University had discove

4、red a magical dose that melts fat in a matter of weeks - resonated with unusual force. Momentarily, at least, it encouraged the spirits of millions of lifelong dieters and boosted the stock of Amgen, the biotechnical firm based in California that holds the license on the underlying technology. It is

5、 too early to predict, however, whether this rare elixir (called leptin, after the Greek leptos, meaning slender) will be a stunning pharmaceutical (制药上的 ) success or just another “miracle“ cure that never pans out. Even if all goes well, it could be five to ten years before leptin is approved in th

6、e US for human use. Researchers must first demonstrate that leptin benefits people as well as animals and that it causes no serious side effects. The search for leptin began in the 1960s, when Douglas Coleman, a researcher at the Jackson Laboratory in Bar Harbor, Maine, began studying a strain of fa

7、t laboratory mice. In a series of creative experiments, Coleman surgically joined the blood vessels of an .obese (肥胖的 ) mouse to those of a normal-size mouse, creating a sort of artificial Siamese twin. What happened then was astonishing: the fat animal immediately began to lose weight. This suggest

8、ed that the blood of non-obese mice carried an effective biochemical messenger, one that played an important role in regulating appetite and metabolism (新陈代谢 ). But the mysterious agent was present in such minuscule quantities that no one was able to isolate it. Friedman picked up the challenge, app

9、lying new tools developed by the field of molecular genetics. The secret factor, he reasoned, must be produced by a gene that was defective in the obese mice. So he began to hunt for such a gene, the ob, or obese, gene. Sure enough, late last year, after eight years of effort, Friedman and his colle

10、agues pinpointed the ob gene in both average-weight and obese mice. They then inserted the normal gene into bacterial (细菌的 ) cells, providing at long last detectable quantities of the protein they called leptin. By injecting leptin into obese mice, three separate teams of researchers, including Frie

11、dmans, have confirmed that this protein is indeed the blood factor that makes fat mice thin. But they are still trying to puzzle out just how it works. Friedman, for one, believes leptin is almost certainly a hormone that travels through the bloodstream to act on the brain. In fact, it appears lepti

12、n may act in a feedback loop (反控循环 ) like the temperature sensor in a thermostat (恒温器 )-or in this case a “fatstat“ - to tell the body whether to turn metabolism and appetite up or down. Thus when leptin is low, hunger pangs increase, body temperature drops, and metabolism slows; when leptin is high

13、, everything reverses. In such fashion, the brain strives to keep body weight stable and fluctuations small. Because leptin is produced in fat tissue (组织 ), the fatter an animal is, the more leptin its cells should make. Normal mice then respond to weight gain by turning out more leptin. As a result

14、, their appetites slow down and their energy consumption speeds up. But the obese mice cannot produce leptin, so their brains never receive this vital message. “These animals,“ says Friedman, “get fat because they think theyre starving, and then when we give them the protein, they get thin because t

15、hey think theyre fat!“ What, if anything, does this have to do with people? Perhaps a good deal. For humans have an ob gene that is virtually the same as the mouse gene, and it is possible that at least some folks have trouble keeping off kilos because of mutation (突变 ) in this gene. Most experts, h

16、owever, agree that defects in the ob gene are not likely to be a major reason for obesity in people. But that does not mean leptin might not be therapeutically (治疗学的 ) useful for many other overweight people. In last weeks Science, for example, a team of researchers from the pharmaceutical company H

17、offmann-LaRoche described how they fattened lean mice by giving them unrestricted access to high-fat food. Then they administered leptin. The mice responded by cutting their food intake and shedding the extra grams, suggesting leptin may have value in reversing more typical cases of weight gain. Wha

18、t about side effects? Injections of leptin do not, as one might fear, turn lean mice into starving wretches. After losing weight, researchers from Amgen reported, normal mice stabilize both their food intake and their metabolism. Obese mice likewise reach an ideal leanness, and then stop losing weig

19、ht. The pattern of weight loss is also encouraging. For unlike extreme calorie restriction, which can weaken muscle, leptin appears to melt fat while leaving lean tissue untouched. On the basis of such data, Amgen (which paid Rockefeller University $ 20 million for patent rights to make products bas

20、ed on the ob gene) has announced that it hopes to begin making human trials as early as next year. Many experts find these plans too optimistic. Just because researchers have not noted worrisome side effects yet, critics say, does not mean that none will emerge. Leptin, they point out, is a serious

21、drug, not the easy-to-swallow “thin pill“ dieters have dreamed of for so long. To do its work, leptin would probably have to be either injected daily or implanted under the skin for life. In the laboratory experiments reported last week, the obese mice started regaining weight as soon as the injecti

22、ons stopped. Even with a boost from something like leptin, cautions Dr. Ahmed Kissebah, an obesity expert at the Medical College of Wisconsin, the formerly fat cannot afford to become less alert. “People will still have to lose weight the hard way,“ he predicts. “Itll be like diabetes: you still hav

23、e to exercise and watch your food intake.“ Regardless of what eventually happens in the marketplace, the discovery of leptin is occasion for celebration. It has provided scientists with a new way for exploring a still poorly understood metabolic pathway, one that probably consists of many other equa

24、lly powerful compounds, each of which could lead to new drugs. To the millions of seriously overweight Americans, help with a frustrating condition - years of guilty eating and self-recrimination - may finally be on the way. 2 Leptin is effective in reducing weight but its many years away before hum

25、ans can use it. （ A） Y （ B） N （ C） NG 3 Leptin, after being approved by health authorities, will be available to people in need through doctors prescriptions. （ A） Y （ B） N （ C） NG 4 Both obese mice and normal mice have the ob gene. （ A） Y （ B） N （ C） NG 5 Both obese mice and normal mice can produce

26、 leptin in their bodies. （ A） Y （ B） N （ C） NG 6 Dr. Friedman never found the gene that was believed to control weight. Instead, he found leptin. （ A） Y （ B） N （ C） NG 7 If excess leptin is present, the brain signals the body to increase food intake and to become more active. （ A） Y （ B） N （ C） NG 8

27、 The ob gene causes the fat cells to produce the hormone leptin. The fatter, the more hormones are produced. （ A） Y （ B） N （ C） NG 9 Leptin plays an important role in adjusting _ and metabolism. 10 After being _ leptin, the obese mice start consuming less food and burning more fat, which is confirme

28、d by Friedman together with three separate teams of researchers. 11 In response to _, normal mice will turn out more leptin that will speed up their energy consumption. Section A Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversatio

29、n, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer. （ A） She hasnt cleaned

30、her room either. （ B） She left her room on time this morning. （ C） She can help the man clean up his room. （ D） She doesnt know the mess the man have made in her room. （ A） The man should watch a different program. （ B） Shed like to watch television with the man. （ C） The man shouldnt waste his time

31、 watching television. （ D） The television program doesnt start until later in the evening. （ A） He hadnt noticed a lot of the womans mistakes. （ B） Hes not qualified to proofread the womans report. （ C） He thinks the woman should have asked him earlier. （ D） Hell be able to talk to the woman in a fe

32、w minutes. （ A） She lost Sallys new address. （ B） Sally had to move unexpectedly. （ C） Shes no longer in contact with Sally. （ D） Shell be glad to take the mail to Sallys house. （ A） He had to cancel his interview. （ B） Hes disappointed with his interview. （ C） He shouldnt have applied for the job.

33、（ D） He doesnt want to discuss the interview now. （ A） At 9: 00. （ B） At 9: 15. （ C） At 9: 30. （ D） At 10: 00. （ A） She didnt go to the game. （ B） She also left the game early. （ C） Shes also curious about who won the game. （ D） She was sitting right behind the man at the game. （ A） She had to wait

34、even longer than the man did to have her car inspected. （ B） The man should have had his car inspected earlier. （ C） The auto inspection center will be closed at the end of the month. （ D） The man doesnt need to have his car inspected until next month. （ A） That the library opens at 8:00. （ B） That

35、no one else has read the articles. （ C） That none of the material he needs is available. （ D） That reserve materials can be taken out of the library. （ A） He is not cooperative. （ B） He will be in his office all afternoon. （ C） He has not read any of the articles himself. （ D） He already brought in

36、extra copies of the articles. （ A） Return early the next day. （ B） Photocopy the articles he needs. （ C） Ask professor Grand for a copy of the articles, （ D） Wait until the girl has finished with her articles, （ A） More work as an instructor. （ B） A higher salary. （ C） A longer vacation period. （ D）

37、 A research assignment. （ A） Hell start next week. （ B） He wouldnt enjoy it. （ C） He would like time to decide. （ D） He wants his advisers opinion. （ A） Finish his degree in the fall. （ B） Let someone else read his evaluation. （ C） Consider taking fewer courses. （ D） Get more teaching experience. （

38、A） Franks talent for teaching. （ B） Franks interesting approach to research. （ C） A present he received for graduation. （ D） A congratulatory letter from the department. Section B Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. B

39、oth the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D. （ A） Because the shape of snow crystal(晶体 ) is still a mystery for experts. （ B） Because the snowfall is a blessing for human beings. （ C

40、） Because experts have different ideas about the formation of snowflakes. （ D） Because it is not easy to judge the time or place of snowfall. （ A） Area. （ B） Temperature. （ C） Climate. （ D） Season （ A） Snow crystals may stick together to make a snowflake. （ B） Dusts may join together to form a snowf

41、lake. （ C） Snowflakes is produced by snow storms. （ D） Raindrops may freeze to form snowflakes. （ A） In 1930s. （ B） In 1970s. （ C） In 1940s. （ D） In 1980s. （ A） A worker can invest 4,500 into IRA while he can put only 4,000 into the pension. （ B） The .saver of IRA can decide the investment of the ac

42、count. （ C） In IRA savings can be withdrawn freely and this is not allowed in pension. （ D） Money put in IRAs will be taxed and money in pension is tax-free. （ A） The money will be taxed like expenditure. （ B） The account holder will be fined. （ C） He might be fired by his working place. （ D） He mig

43、ht be prevented from claiming tax reductions. （ A） Unfriendliness. （ B） Generosity. （ C） Friendship. （ D） Strength. （ A） To present his hands palm to palm. （ B） To extend his hand to his superior. （ C） To raise his hand above his head. （ D） To put his hand upon his chest. （ A） Greeks. （ B） Arabians.

44、 （ C） Indians. （ D） Chinese. （ A） The use of hands. （ B） Different ways of expressing politeness. （ C） Customs of ancient times. （ D） The meaning of the hand and its actions. Section C Directions: In this section, you will hear a passage three times. When the passage is read for the first time, you

45、should listen carefully for its general idea. When the passage is read for the second time, you are required to fill in the blanks numbered from 36 to 43 with the exact words you have just heard. For blanks numbered from 44 to 46 you are required to fill in the missing information. For these blanks,

46、 you can either use the exact words you have just heard or write down the 37 Good evening, welcome to the first meeting of our spring【 B1】 season. Its a pleasure to see so many new faces here. I certainly hope that most of you will soon feel right with our group and bicycling will become a regular【

47、B2】 for you and a part of your physical fitness routine. Some of you may not realize that the state of New Jersey offers ample (充足的 )【 B3】 for bicyclists of all abilities. We have【 B4】 country side, miles of beaches, lovely hills and valleys and thousands of miles of little used roads. Beginners wil

48、l find the shore and area south of Princeton suitable for their needs while【 B5】 riders will discover that the steep trails of the region around high point offer a【 B6】 to their skill and stamina (耐力 ). In addition, New Jersey is rich in places of historical interest. The state abounds (富于 ) in【 B7】

49、 architectures, battle fields of the【 B8】 and other historic sites important in the early history of this country. Most of them are carefully preserved or have been carefully restored.【 B9】 . Next Saturday tour will be a relatively easy one, from Recters University to the gate of National Park. Interested bicyclists should meet at eight a.m. in the parking lot at the comer of Hamilton Street and Coolidge Avenue in New Branderswick.【 B10】 Well use a buddy system throughout our ride. Each r