1、大学英语六级 52及答案解析(总分：448.05，做题时间：132 分钟)一、Part I Writing (3(总题数：1，分数：30.00)1.For this part, you are allowed 30 minutes to write a short essay entitled Graduate School or Work? You should write at least 150 words following the instructions given below: 目前，越来越多的大学生本科毕业之后选择继续进入研究生院学习。一个重要的原因是工作不太好找。那么你打算在
2、大学毕业之后找工作还是继续上研究生呢?请就这个问题谈谈你的打算和主要原因。 （分数：30.00）_二、Part II Reading C(总题数：1，分数：71.00)Animal tests More than a cosmetic (化妆品) change Every time you reach for an eye-drop or reapply a lip salve, you do be so confident that the chemicals they contain are safe to use. But the toxicology (毒物学) tests on wh
3、ich regulators rely to gather this information are largely based on wasteful and often poorly predictive animal experiments. Efforts in Europe are about to change this, and the man charged with bringing toxicology into the twenty-first century is a plain-talking German: Thomas Hartung. Although Hart
4、ung acknowledges the immense challenges ahead, he sees this as an opportunity for toxicology “to turn itself at last into a respectable science“. Three years ago, when Hartung became director of the European Centre for the Validation of Alternative Methods (ECVAM) in Ispra, Italy. ECVAM was set up i
5、n 1993 to support European Union policy aimed at reducing the number of animals used in regulatory testing. The centre, which sits on the sleepy shores of Lake Maggiore in the Italian Alps, originally had ten members of staff and faced an uphill struggle to cut back the millions of animal tests carr
6、ied out in Europe every year. Then in 2003, two major policy changes were announced from above, increasing the pressure on the centres labs. ECVAM found itself facing an unexpectedly short deadline for delivering a slew of animal-free methods for testing chemical toxicity. Rule change The first chan
7、ge was to the European Unions Cosmetics Directive, which phases out over ten years the use of animals in cosmetics testing. A short while later, the European Commission proposed its controversial REACH legislation (Registration, Evaluation and Authorization of Chemicals). Europe produces some 30,000
8、 chemicals for which toxicity data have never been registered. REACH aims to make registration mandatory for both future and existing chemicals even those that have been on the market for decades. If, as expected, the REACH directive is approved next year, it will come into effect in 2007. Animal-we
9、lfare groups fear that this will mean millions more animals will be used in tests to meet the regulatory requirements. And industry claims that the testing process could cost billions of euros. Almost overnight, industrys interest in cheaper, animal-free testing skyrocketed. Last month ECVAM was put
10、 in charge of developing, with industry and regulatory agencies, the testing strategies for REACH. Now commanding 50 staff, Hartung is rising to the challenge. “The toxicity tests that have been used for decades are simply bad science“, he explains. “We now have an opportunity to start with a clean
11、slate and develop evidence-based tests that have true predictive value.“ Many of the animal tests used today were developed under crisis conditions. The notorious Draize test, which assesses the irritation or damage caused by chemicals simply by putting them into the eyes of rabbits, is a prime exam
12、ple. It was developed by the US Food and Drug Administration in 1944 after reports in the 1930s that some cosmetics were causing permanent eye injuries. One 38-year-old woman had gone blind after dyeing her lashes with Lash-Lure, a product that contained a derivative of coal tar. Then came the calam
13、ity of thalidomide (镇静剂), which was given to pregnant women in the late 1950s to control morning sickness, but which caused horrific birth defects. By this time, governments were highly sensitive to public concerns and called on their authorities to develop animal-based tests that would predict all
14、conceivable toxic effects of drugs and chemicals. The principles behind most of those tests remain more or less unchanged today. Safety catch Each chemical that goes through the multiple tests required for registration can use up to 5,000 animals or 12,000 if the chemical is a pesticide. The cost of
15、 doing this for the 30,000 unregistered chemicals so that they comply with REACH has been estimated at between 5 billion (US$6 billion) and 10 billion. In the decade since ECVAM was established, the number of animals used in toxicology testing has fallen slightly, although it still hovers at about o
16、ne million per year. This reduction is a result of the refinement of existing tests, and the introduction of some alternative methods that rely on in vitro (试管) tests using cell cultures. ECVAM believes that it can halve the total number of animals used for regulatory testing within a decade. It has
17、 just completed its first large-scale validation study of an in vitro cytotoxicity test, which monitors death of cultured cells following short-term exposure to a chemical. Chemicals shown to be harmful in this test would be excluded from any LD50 animal tests. At least 70% of the chemicals register
18、ed in the past two decades fall into this category, says Hartung. And this is just the beginning. Poor prediction Most animal tests over-or under-estimate toxicity, or simply dont mirror toxicity in humans very well. The relevant industries also acknowledges the poor quality of those tests. Take the
19、 embryotoxicity test in which chemicals are fed to pregnant animals and the fates of their embryos, and the progeny of two subsequent generations, are studied. “Animal embryotoxicity tests are not reliably predictive for humans,“ says Horst Spielmann, a toxicologist at the Federal Institute for Risk
20、 Assessment in Berlin. “When we find that cortisone is embryotoxic in all species tested except human, what are we supposed to make of them?“ The same goes for cancer. To test a single chemical for its potential to cause cancer takes five years and involves 400 rats, each of which is treated with th
21、e maximum tolerated dose. It is dramatically over-predictive: more than 50% of the results are positive, of which 90% are false positive. Yet the number of compounds proved to be carcinogenic to humans is very low the International Agency for Research on Cancer in Lyons, France, has identified just
22、95 proven and 66 probable human carcinogens (致癌物质). Life or death Scientists also cannot assume that in vitro alternatives are automatically better, says Spielmann. In 1971, a comparison of animal Draize tests in different labs revealed the test to be hopelessly non-reproducible. But Spielmanns 1995
23、 study of animal-free alternatives to the Draize test showed that they were equally unreliable. Since then the in vitro tests have been standardized, and they are intrinsically more reproducible. “Although reproducibility and relevance are not the same thing,“ Spielmann cautions. Relevance requires
24、a good match between the test results and human data. At an ECVAM workshop in February, 30 industrial scientists met to develop the most effective strategy for using the alternative Draize tests, so that the false negatives and false positives of each test compensate for each other. This strategy is
25、 now going through the crucial validation procedure, in which human data, often from occupational health databases, will be used as points of reference. ECVAM has so far seen 17 alternative tests through validation 11 use in vitro methods, another six involve refining in vivo tests to reduce the num
26、ber of animals used. Most of the new tests assess acute toxicity, but animal use is highest when testing for the toxic effects of prolonged exposure to chemicals for long-term consequences such as cancer and reproductive toxicity. These costly procedures are harder to mimic in vitro and may never be
27、 completely replaced. Sounds familial This is why, apart from the 30 million it uses to support ECVAM annually, the European Commission is funding three multimillion-euro Integrated Projects. Under these, dozens of labs will collaborate for five years to tackle more difficult issues, such as allergi
28、c reactions (过敏反应) or widespread toxicity resulting from chemicals entering the bloodstream. Scientists know that they are likely to find it hardest to convince regulators about alternative tests for highly emotive issues such as cancer and birth defects. More than half of all animals that will be n
29、eeded to support REACH legislation are likely to be used in reproductive toxicology testing. The 9-million Integrated Project called ReProTect has 27 labs dedicated to developing alternatives to these tests. The ReProTect consortium has broken down the human reproductive cycle into smaller elements,
30、 from male and female fertility to implantation, to pre-and postnatal development, and is trying to develop a meaningful package of tests. “Quite correctly everyone feels uneasy about taking risks where stakes are so high and issues so emotive,“ says Hartung. “We all want to be sure that there is re
31、al evidence that alternative tests are predictive of human toxicity.“ For example, regulators know the weaknesses of the rat cancer test as well as scientists but, wanting to be safe rather than sorry, they accept it because it is believed to throw up few false negatives. They prefer to let industry
32、 prove the innocence of any compound that shows up positive. Any replacement tests will need to reassure both regulators and industry. （分数：71.00）(1).Most toxicology tests for cosmetics are often poorly predictive animal experiments.（分数：7.10）A.YB.NC.NG(2).Thomas Hartung is an Italian.（分数：7.10）A.YB.NC
33、NG(3).European Unions Cosmetics Directive has 50 staff.（分数：7.10）A.YB.NC.NG(4).According to Hartung, the toxicity tests used for tens of years are simply bad science.（分数：7.10）A.YB.NC.NG(5).Thalidomide used in the late 1950s to control morning sickness caused_.（分数：7.10）_(6).ECVAM believes that the re
34、fined in vitro test method can reduce by halve _used for regulatory testing within a decade.（分数：7.10）_(7).How is an embryotoxicity test carried out?（分数：7.10）_(8).From the passage we know that results of cancer tests on animals are often_.（分数：7.10）_(9).Reproducibility and relevance differ in the sens
35、e that relevance requires_.（分数：7.10）_(10).Scientists think that they may find it most difficult to persuade regulators to use alternative tests for_.（分数：7.10）_三、Listening Comprehens(总题数：1，分数：15.00)A.He may convert it and use it as a restaurant.B.He may pull it down and build a new restaurant.C.He ma
36、y rent it out for use as a restaurant.D.He may sell it.A.The woman is upset because she didnt pass the examination.B.The woman doesnt hope for a promotion.C.The man gets used to counting on the woman.D.The man thinks that the women should be promoted.A.He is very quiet.B.He gives amusing lectures.C.
37、He should give more than one series of talks.D.He lectures only to the serious students.A.Mark doesnt like water.B.Mark doesnt belong here.C.Mark is like a fish.D.Mark is in this class.A.He was very slow in doing things.B.He was the right person to do such a thing.C.He is expected to do such a thing
38、D.He would never do such a thing.A.A stormy ocean.B.Calm water.C.Golden sand.D.Little waves.A.He lost a button at work.B.He doesnt know where he put the calculator.C.He thinks he broke something the woman lent him.D.Hes not sure how to solve the math problem.A.He is having a hard time letting his a
39、partment.B.He prefers his old tenant to the new one.C.He is not accustomed to living with the new tenant yet.D.He doesnt want to lend his apartment to her.四、Section A(总题数：2，分数：10.00)A.He was looking for a job.B.He seemed to have many needed qualifications.C.He handed in his application earlier than
40、others.D.He needed a position in the company.A.The company was a small, family-owned company.B.The company gave a lot of responsibilities to the employees.C.The company required the employees to be loyal and hard-working.D.The company would soon raise the employees salary.A.The woman was not satisfi
41、ed with the man.B.The woman would choose other candidates for the position.C.The man was very likely to be employed.D.The man was disappointed with the company.A.Three hour and a half.B.Thirty minutes.C.Four hours.D.180 minutes.A.Beside the door.B.On the desk.C.In her hands.D.Near the desk.A.The wai
42、ter.B.The clerk.C.Nobody.D.The woman herself.五、Section B(总题数：3，分数：30.00)A.To find out whether they take music lessons in their spare time.B.To find out whether they can name four different musical instruments.C.To find out whether they enjoy playing musical instruments in school.D.To find out whethe
43、r they differ in their preference for musical instruments.A.They find them too hard to play.B.They think it silly to play them.C.They find it not challenging enough to play them.D.They consider it important to be different from girls.A.Children who have private music tutors.B.Children who are 8 or o
44、lder.C.Children who are between 5 and 7.D.Children who are well-educated.A.Because there are no signs to direct them.B.Because no tour guides are available.C.Because all the buildings in the city look alike.D.Because the university is everywhere in the city.A.They set their own exams.B.They select t
45、heir own students.C.They award their own degrees.D.They organize their own laboratory work.A.Most of them have a long history.B.Many of them are specialized libraries.C.They house more books than any other university library.D.They each have a copy of every book published in Britain.A.Very few of th
46、em are engaged in research.B.They were not awarded degree until 1948.C.They have outnumbered male students.D.They were not treated equally until 1881.A.Energy conservation.B.A new kind of transportation.C.Strip cities.D.Advantages of air transportation over rail roads.A.On short trips.B.On long trip
47、s.C.When flying over cities.D.When flying at high altitude.A.It uses nuclear energy.B.It rests on a cushion of professional air.C.It flies over magnetically activated tracks.D.It uses a device similar to a jet engine.A.It is more comfortable than a conventional train.B.It doesnt require much track maintenance.C.It doesnt remain in any station very long.D.It carries more passengers than a conventional train.六、Section C(总题数：1，分数：10.00)Nightmare disorder, which is also called dream dis
