1、大学英语六级 56 及答案解析(总分：448.03，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 composition on the topic: A Letter to My High School Teacher. You should write at least 150 words, and base your composition on the outline given below in Chinese. 假设你是张英，你
2、考入大学后，给你的中学老师写一封信，信的内容除了对老师问候外，主要讲一讲大学的生活和学习与中学的不同。 （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
3、学) tests on which 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.
4、 Although Hartung 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. ECVA
5、M was set up in 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 ani
6、mal tests carried 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
7、The first change 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 produc
8、es some 30,000 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 2
9、007. Animal-welfare 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
10、 ECVAM was put 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
11、 with a clean 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, i
12、s a prime example. 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
13、came the calamity 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 woul
14、d predict all 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 pesticid
15、e. The cost of 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 hov
16、ers at about one 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
17、decade. It has 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 chem
18、icals registered 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 t
19、ests. Take the 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 Inst
20、itute for Risk 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 t
21、reated with the 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 id
22、entified just 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 S
23、pielmanns 1995 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. Relev
24、ance requires 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. Th
25、is strategy is 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
26、reduce the number 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 an
27、d may never be 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, s
28、uch as allergic 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
29、that will be needed 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 sma
30、ller elements, 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 th
31、at there is real 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 t
32、o let industry 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
33、数：7.10）A.YB.NC.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 believ
34、es that the refined 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 diff
35、er in the sense 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.Tim will surely come to repair the walkman.B.Tim is very trustworthy.C.Tim cannot repai
36、r the walkman.D.Tim doesnt keep his word.A.She wants a copy of the article.B.She doesnt want the copy because it costs too much.C.The article is much too difficult to understand.D.It doesnt matter to her.A.The man doesnt have to study a foreign language.B.The man just passed the foreign language tes
37、t.C.The mans advisor gave him some good advice.D.The man doesnt have to take the final exam.A.The man would understand if he had Peters job.B.Peter could help him get a job on an airplane.C.Waiting on tables is an enjoyable job.D.She is tired of waiting for him there.A.Mark is going to Spain.B.Mark
38、has traveled all over the world.C.Mark has the habit of collecting postcards.D.Mark is going on vacation.A.They cost her lots of money.B.They are very rewarding.C.They are very easy to learn.D.They are given by a strict teacher.A.The admission of a patient.B.Diagnosis of an illness.C.The old mans se
39、rious condition.D.Sending for a doctor.A.The man is a football fan.B.The man needs the womans help.C.The man didnt watch TV last night.D.The man often has power failure at home.四、Section A(总题数：2，分数：10.00)A.Inviting him to dinner.B.Inviting him to a party.C.Asking him for money.D.Asking him to talk t
40、o his girlfriend.A.They have a big fight.B.They have a quarreling.C.They are breaking up.D.They will get married.A.Talk to his girlfriend.B.Recover with his girlfriend.C.Invite her to the party.D.He didnt be certain.A.Memories of a recent storm.B.How strong winds develop into a hurricane.C.Weather p
41、atterns that can affect Florida.D.Planning a summer vacation.A.By name.B.By number.C.By location.D.By month.A.Study a weather map.B.Visit a weather station.C.Watch a weather report.D.Go to a storm shelter.五、Section B(总题数：3，分数：30.00)A.Quite similar.B.Not similar.C.Exactly the same.D.Greatly different
42、.A.Your ears.B.Your body.C.Your brain and your ears.D.Your ears and your whole body.A.Brain.B.Heart.C.Brain and muscle.D.Brain and heart.A.To explain why people fail to act in emergencies.B.To explain when people will act in emergencies.C.To explain what people will do in emergencies.D.To explain ho
43、w people feel in emergenciesA.They are afraid of emergencies.B.They are reluctant to get themselves involved.C.Others will act if they themselves hesitate.D.They do not have any direct responsibility for those who need help.A.We shouldnt blame a person if he fails to act in emergencies.B.A person mu
44、st feel guilty if he fails to help.C.People should be responsible for themselves in emergencies.D.When you are in trouble, people will help you anyway. Passage ThreeA.The color of the dog.B.The price of the dog.C.Whether the dog will fit the environment.D.Whether the dog will get along with the othe
45、r pets in the house.A.It must be trained so it wont bite.B.It needs more love and care.C.It demands more food and space.D.It must be looked after carefully.A.They are less likely to run away.B.Its easier for their masters to train them.C.They are less likely to be shy with human beings.D.Its easier
46、for them to form a relationship with their masters.六、Section C(总题数：1，分数：10.00)More and more, the operations of our businesses, governments, and (36) 1institutions are controlled by information that exists only inside computer memories. Anyone clever enough to (37) 2 this information for his own purp
47、oses can reap (收割) substantial rewards. Even worse, a number of people who have done this and been caught at it have (38) 3 to get away without punishment. Its easy for computer crimes to go (39) 4 if no one checks up on what the computer is doing. But even if the crime is detected, the criminal may walk away not only unpunished but with a glowing (40) 5from his former employers. Of course, we have no (41) 6on crimes that go undetected. But its (42) 7to note how many o
