大学英语四级-124及答案解析.doc

1、大学英语四级-124 及答案解析(总分：20.00，做题时间：90 分钟)一、Reading Comprehensio(总题数：4，分数：20.00)1.In a step that should help make the Internet safer for consumers, anti-virus giant Symantec on Wednesday will introduce a protection system designed to anticipate new ill-meaning programs that try to steal onto your compute

2、r. For decades, anti-virus protection has worked by reacting to new ill-meaning programs. Researchers rush to identify bad code, then create and distribute filters for it. But cybercriminals have got so fast at escaping the latest filters that protection often comes too late. Symantec“s new system,

3、called Quorum, continuously predicts whether any new program that attempts to run on your PC is good or bad. It then takes steps to isolate the bad code. “We“re closing a major gap the bad guys have been using to deriver their ill-meaning software,“ says Rowan Trollope, senior vice president of cons

4、umer products. Symantec becomes the fourth major anti-virus firmand the largestto add predictive capabilities to traditional reactive anti-virus systems. Since February, McAfee, Panda Security and Trend Micro have introduced similar predictive technologies. Computer infections most often spread when

5、 a PC user clicks on an altered Web link that arrives in an e-mall or social-network message, or appears in search results for questions on Google, Bing and Yahoo Search. What“s more, millions of lawful Web pagesunknowingly altered by hackerscan also infect a PC during a page visit. Cybercriminals u

6、se infected PCs to spread junk e-mails, steal data and hijack online banking accounts. Infections can change hourly, forcing anti-virus firms to create and deliver thousands of filters each day. “The amount of ill-meaning software produced today has required all of us to change the approach we take

7、in combating it,“ says Trend Micro senior manager Jon Clay. Trend began offering predictive protection to business customers in May. A consumer version is due next year. “There is a natural evolution taking place,“ says Mike Gallagher, chief technology officer for McAfee, which roiled out its Artemi

8、s system for consumers and businesses in February. Symantec introduces Quorum in its new Norton Internet Security 2010 system for consumers priced at $70 for a one-year subscription; McAfee“s consumer subscription is priced similarly. Panda Security“s free consumer version of its Panda Cloud anti-vi

9、rus product has been out since April.In the past decades, anti-virus protection hasn“t worked effectively because _.（分数：5.00）A.researchers didn“t create filters in timeB.filters were soon escaped by cybercriminalsC.ill-meaning programs were too complexD.cybercriminals were smarter than researchers2.

10、Henry III didn“t know much about biology. He went through six wives back in the 1500s, looking for one who could bear him a son. Scientists now know that it“s the father“s sperm, not the mother“s egg, which determines whether a baby is a boy or a girl. And last week researchers at the Genetics and I

11、VF Institute, a private fertility (生育能力) center in Virginia, announced a new technique that will allow parents to choose the sex of their baby-to-be, before it has even been conceived. The scientist used a tiny laser detector to measure the DNA in millions of sperm cells as they pass single file thr

12、ough a narrow tube, like cattle being herded through a corral (牲口栏). In a study published last week, “girl sperm,“ which has more DNAthe genetic materialin each cell, was collected, while “boy sperm“ was discarded. And when purified girl sperm was used to impregnate (使受孕) a group of mothers, 15 of 1

13、7 resulting babies turned out to be girls. The researchers say that “sex selection“ can also double a mother“s chance of having a son and can be used to avoid genetic diseases that affect only one gender, such as hemophilia (血友病). But some experts, like New York University fertility specialist Dr. J

14、amie Grifo, worry that sex selection could lead to a kind of in uteri (子宫) discrimination, especially in cultures where sons are considered superior to daughters. “It“s valuing one gender over another,“ Grifo says. “I don“t think that“s something we should be doing.“ So far, patients at the institut

15、e have been asking for both boys and girls, in order to “balance“ their families. And some ethics experts say that“s free, as long as parents are just looking for a little gender variety. “If you have three boys, and you want a girl,“ says University of Texas reproductive-law professor John Robertso

16、n, “that“s not gender bias at all.“The DNA in the sperm cells can be measured _.（分数：5.00）A.in the same way how the cattle are herdedB.when they pass through a tube one behind the otherC.after they pass through a laser tubeD.when they are scanned by a laser detector all at a time3.How does food affec

17、t mood and mind? The answer may lie in the chemistry of the brain and nervous system. Molecules called neurotransmitters (神经传递素) are chemical messengers. They carry a nerve impulse across the gap between nerve cells. The release of neurotransmitter molecules from one neuron and their attachment to r

18、eceptor sites on another keep a nerve impulse moving. Nerve impulses carry messages from the environment to the brain, for example, the pain you feel when you stub (踢碰) your toe. They also carry messages in the other direction, from the brain to the muscles. That“s why you back away from the obstacl

19、e that initiated the pain signal and exclaim, “Ouch!“ “Many neurotransmitters are built from the foods we eat,“ says neuroscientist Eric Chudler of the University of Washington. Too little or too much of a particular nutrient in the diet can affect their production, Chudler says. For example, trypto

20、phan from foods such as yogurt, milk, bananas, and eggs is required for the production of the neurotransmitter serotonin. Phenylalanine from beets, almonds, eggs, meat, and grains goes into making the neurotransmitter dopamine. Dozens of neurotransmitters are known; hundreds may exist. Their effects

21、 depend on their amounts and where they work in the brain. The neurotransmitter serotonin, for example, is thought to produce feelings of calmness, relaxation, and contentment. Drugs that prevent it from being taken again (into the neuron that released it) are prescribed to treat depression. In at l

22、east some healthy, nondepressed people, carbohydrate foods seem to enhance serotonin production and produce similar effects. “It is the balance between different neurotransmitters that helps regulate mood,“ Chudler says. Proper nutrition may also enhance brainpower. Choline is a substance similar to

23、 the B vitamins. It“s found in egg yolks, whole wheat, peanuts, milk, green peas, liver, beans, seafood, and soybeans. The brain uses it to make the neurotransmitter acetylcholine. To test the effects of choline on memory and learning, researchers at the Massachusetts Institute of Technology gave me

24、mory tests to college students before increasing the amount of choline in their subjects“ diets. Later, they retested. On the average, memories were better, and the students learned a list of unrelated words more easily.The function of neurotransmitters can be best compared to that of _.（分数：5.00）A.a

25、 transport vehicleB.a protective shieldC.a power plantD.a food factory4.Like a needle climbing up a bathroom scale, the number keeps rising. In 1991, 15% of Americans were obese (配胖的); by 1999, that proportion had grown to 27%. Youngsters, who should have age and activity on their side, are growing

26、larger as well: 19% of Americans under 17 are obese. Waistbands have been popping in other western countries too, as physical activity has declined and diets have expanded. By and large, people in the rich world seem to have lost the fight against flab (松弛). Meanwhile, poorer nations have enjoyed so

27、me success in their battles against malnutrition and famine. But, according to research presented at the annual meeting of the American Association for the Advancement of Science, it is more a case of being out of the frying pan and into the fire. The most striking example actually in the poor world

28、 comes from the Pacific islands, home of the world“s most obese communities. In 1966, 14% of the men on this island were obese while 100% of men under the age of 30 in 1996 were obese. This increase in weight has been uneven as well as fast. As a result, undernourished and over-nourished people freq

29、uently live cheek by jowl (面颊 ). The mix can even occur within a single household. A study of families in Indonesia found that nearly 10% contained both the hungry and the fat. This is a mysterious phenomenon, but might have something to do with people of different ages being given different amounts

30、 of food to eat. The prospect of heading off these problems is bleak. In many affected countries there are cultural factors to contend with, such as an emphasis on eating large meals together, or on food as a form of hospitality. Moreover, there is a good measure of disbelief on the part of policyma

31、kers that such a problem could exist in their countries. Add to that reluctance on the part of governments to spend resources on promoting diet and exercise while starvation is still a real threat, and the result is a recipe for inaction. Unless something is done soon, it might not be possible to tu

32、rn the clock back.The first sentence of the passage most probably implies that _.（分数：5.00）A.many Americans are obsessed with the rising temperature in their bathroomB.more people are overweighed in the United StatesC.people are doing more physical exercises with the help of scalesD.youngsters become

33、 taller and healthier thanks to more activities大学英语四级-124 答案解析(总分：20.00，做题时间：90 分钟)一、Reading Comprehensio(总题数：4，分数：20.00)1.In a step that should help make the Internet safer for consumers, anti-virus giant Symantec on Wednesday will introduce a protection system designed to anticipate new ill-meanin

34、g programs that try to steal onto your computer. For decades, anti-virus protection has worked by reacting to new ill-meaning programs. Researchers rush to identify bad code, then create and distribute filters for it. But cybercriminals have got so fast at escaping the latest filters that protection

35、 often comes too late. Symantec“s new system, called Quorum, continuously predicts whether any new program that attempts to run on your PC is good or bad. It then takes steps to isolate the bad code. “We“re closing a major gap the bad guys have been using to deriver their ill-meaning software,“ says

36、 Rowan Trollope, senior vice president of consumer products. Symantec becomes the fourth major anti-virus firmand the largestto add predictive capabilities to traditional reactive anti-virus systems. Since February, McAfee, Panda Security and Trend Micro have introduced similar predictive technologi

37、es. Computer infections most often spread when a PC user clicks on an altered Web link that arrives in an e-mall or social-network message, or appears in search results for questions on Google, Bing and Yahoo Search. What“s more, millions of lawful Web pagesunknowingly altered by hackerscan also inf

38、ect a PC during a page visit. Cybercriminals use infected PCs to spread junk e-mails, steal data and hijack online banking accounts. Infections can change hourly, forcing anti-virus firms to create and deliver thousands of filters each day. “The amount of ill-meaning software produced today has requ

39、ired all of us to change the approach we take in combating it,“ says Trend Micro senior manager Jon Clay. Trend began offering predictive protection to business customers in May. A consumer version is due next year. “There is a natural evolution taking place,“ says Mike Gallagher, chief technology o

40、fficer for McAfee, which roiled out its Artemis system for consumers and businesses in February. Symantec introduces Quorum in its new Norton Internet Security 2010 system for consumers priced at $70 for a one-year subscription; McAfee“s consumer subscription is priced similarly. Panda Security“s fr

41、ee consumer version of its Panda Cloud anti-virus product has been out since April.In the past decades, anti-virus protection hasn“t worked effectively because _.（分数：5.00）A.researchers didn“t create filters in timeB.filters were soon escaped by cybercriminals C.ill-meaning programs were too complexD

42、cybercriminals were smarter than researchers解析：解析 第 2 段第 3 句明确指出保护程序失灵的原因是网络犯罪分子很快能避开过滤器，因此，本题应选 B。2.Henry III didn“t know much about biology. He went through six wives back in the 1500s, looking for one who could bear him a son. Scientists now know that it“s the father“s sperm, not the mother“s eg

43、g, which determines whether a baby is a boy or a girl. And last week researchers at the Genetics and IVF Institute, a private fertility (生育能力) center in Virginia, announced a new technique that will allow parents to choose the sex of their baby-to-be, before it has even been conceived. The scientist

44、 used a tiny laser detector to measure the DNA in millions of sperm cells as they pass single file through a narrow tube, like cattle being herded through a corral (牲口栏). In a study published last week, “girl sperm,“ which has more DNAthe genetic materialin each cell, was collected, while “boy sperm

45、 was discarded. And when purified girl sperm was used to impregnate (使受孕) a group of mothers, 15 of 17 resulting babies turned out to be girls. The researchers say that “sex selection“ can also double a mother“s chance of having a son and can be used to avoid genetic diseases that affect only one g

46、ender, such as hemophilia (血友病). But some experts, like New York University fertility specialist Dr. Jamie Grifo, worry that sex selection could lead to a kind of in uteri (子宫) discrimination, especially in cultures where sons are considered superior to daughters. “It“s valuing one gender over anoth

47、er,“ Grifo says. “I don“t think that“s something we should be doing.“ So far, patients at the institute have been asking for both boys and girls, in order to “balance“ their families. And some ethics experts say that“s free, as long as parents are just looking for a little gender variety. “If you ha

48、ve three boys, and you want a girl,“ says University of Texas reproductive-law professor John Robertson, “that“s not gender bias at all.“The DNA in the sperm cells can be measured _.（分数：5.00）A.in the same way how the cattle are herdedB.when they pass through a tube one behind the other C.after they

49、pass through a laser tubeD.when they are scanned by a laser detector all at a time解析：解析 推理判断题。解答本题的关键在于推断 single file 的意思。该句把精子通过试管的情形与牛群被赶入牲口圈的情形作对比，结合 single 一词本身的意思，可以推断 single file 是“一个接一个”的意思，只有选项 B 能表达这个意思，由此也可否定选项 D。选项 A 最具干扰性，原句是把精子通过试管的情形比作牛群被赶入牲口圈的情形，而选项 A 说的是测定精子内 DNA 的方法与放牧的方法相同，显然选项 A 只是引用了原文的某些词语，但表达的意思与原文却截然不同。3.How does food affect mood and mind? The answer may lie in the chemistry of the brain and nervous system. Molecules called neurotransmitters (神经传递素) are chemical messengers. They carry a nerve impulse across the gap between