21、难度B/A级
Eat to Live
A meager diet may give you health and long 1ife，but it’s not much fun—and it might not even be necessary.We may be able to hang on to most of that youthful vigor even if we don，t start to diet until old age.
Stephen Spindler and his colleagues from the University of California at Riverside have found that some of an elderly mouse’s liver genes can be made to behave as they did when the mouse was young simply by limiting its food for four weeks.The genetic rejuvenation won，t reverse other damage caused by time for the mouse，but could help its 1iver metabolize drugs or get rid of toxins.
Spindler’s team fed three mice a normal diet for their whole lives，and fed another three on half-rations。Three more mice were switched from the normal diet to half-feed for a month when they were 34 months old——equivalent to about 70 human years.
The researchers checked the activity of 11，000 genes from the mouse livers.and found that 46 changed with age in the normally fed mice.The changes were associated with things like inflammation and free radical production--probably bad news for mouse health.In the mice that had dieted all their lives，27 of those 46 genes continued to behave like young genes.But the most surprising finding was that the mice that only started dieting in old age also benefited from 70 per cent of these gene changes.
“This is the first indication that these effects kick in pretty quickly,” says Huber Warner from the National Institute on Aging near Washington，D.C..
No one yet knows if calorie restriction works in people as it does in mice, but Spindler is hopeful.“There’s attracting and tempting evidence out there that it will work.”he says.
If it does work in people，there might be good reasons for rejuvenating the liver.As we get older, our bodies are less efficient at metabolizing drugs，for example.A brief period of time of dieting，says Spindler, could be enough to make sure a drug is effective.
But Spindler isn’t sure the trade-off is worth it. “The mice get less disease，they live longer.but they’re hungry,”he says.“Even seeing what a diet does，it’s still hard to go to a restaurant and say：‘I can only eat half of that’.’’
Spindler hopes we soon won’t need to diet at a11.His company，Life Span Genetics in California，is looking for drugs that have the effects of calorie restriction.
练习：
1.According to the passage，which of the following is NOT true?
A)Eating less than usual might make US live longer.
B)If we go Oil a diet when old，we may keep healthy.
C)Dieting might not be needed.
D)We have to begin dieting from childhood.
2.Why does the author mention an elderly mouse in paragraph 2?
A)To describe the influence of old age on mice.
B)To illustrate the effect of meager food on mice.
C)To tell US how mice’s liver genes behave.
D)To inform US of the process of metabolizing drugs.
3.What can be inferred about completely normally fed mice mentioned in the passage?
A)They will not experience free radical production.
B)They will experience more genetic rejuvenation in their lifetime.
C)They have more old liver genes to behave like young genes.
D)They are more likely to suffer from inflammation.
4.According to the author，which of the following most interested the researchers?
A) The mice that started dieting in old age.
B)27 of those 46 old genes that continued to behave like young genes.
C)Calorie restriction that works in people.
D)Dieting that makes sure a drug is effective.
5.According to the last two paragraphs，Spindler believes that
A)calorie restriction is very important to young people.
B)seeing the effect of a diet，people.will eat less than normal.
C)dieting is not a good method to give US health and a long life.
D)drugs do not have the effects of calorie restriction.
标准答案： D,B,D,A,C
22、难度A级
Kasparov：Chess Computers Beatable…For Now
Humans will continue to beat computers for years.but the machines are 1ikely to dominate in matches played over several games，according to the world’s top chess player.
“We will not see a machine replacing a human being in our lifetime.Man will be able to beat a computer in at least one game for a very long time，”Kasparov told a press conference in Moscow a week after settling for a draw in a six.game match with the computer Deep Junior in New York.But while human intuition can provide an advantage in individual games.“Man will never be able to play 8 or 10 games in a row to an equal level，”Kasparov said.He gradually declines for a variety of external factors：the weather，a headache，family strains or whatever.”
In his Man vs.Machine contest in the United States，Kasparov won the first game，but lost the third after committing a mid—game blunder.He then adopted a safety—first strategy, and in the sixth game passed up a chance to win by accepting a draw in a position some analysts said was favourable.
Kasparov—watchers believe he was determined above all not to lose to Deep Junior because he was still smarting from a defeat to another computer, Deep Blue.in 1997.That 10ss clearly rankled Kasparov, and he said at the time that the computer had been receiving assistance from its human operators.
The Russian，who has reigned undisputedly as the world’s top player since 1985，said he was“satisfied overall”with his result against Deep Junior.although“if I’d been in better shape and had more time to prepare the result might have been different.”He stressed the importance of psychology in chess between one human player and another, and described the “psychological discomfort”involved in adapting to a confrontation with a machine.In chess with humans. “you’re always attempting to impose your decisions on the personality of your rival.A game is always an exchange of errors，of imprecision.It’s psychology.There’s never complete exactitude or purity in a game of chess，”he said.“But playing against a machine，beyond a certain point，to win or even to save the game you have to play will absolute exactitude.which is not a human quality.Knowing this specificity of your rival creates a psychological discomfort which is very difficult to overcome.”
Kasparov was at pains to stress that his l 997 defeat was an aberration：“The main thing was to show that what happened then had nothing to do with the fight between man and machine.Any impartial specialist can see that Deep Junior is much stronger than Deep Blue.The real battle begins now.”
1.According to Kasparov，
A)humans can beat computers in individual games.
B)computers will never take the place of human beings in games.
C)human beings can never beat computers in individual or series games
D)human intuition plays an important role in games.
2.In the contest with Deep Junior in the United States，Kasparov
A)lost the game.
B)won the game.
C)settled for a draw.
D)left the game unfinished.
3.Which of the following statements is true about Kasparov’S contest with Deep Blue in 19977
A)He made up his mind to win Deep Blue.
B)He was smart enough to have beaten Deep Blue.
C)Deep Blue received human assistance.
D)Kasparov was unwilling to admit his defeat by Deep Blue.
4.According to Kasparov, a human VS machine chess game may involve all the following qualities EXCEPT that
A)it involves psychological discomfort in the mind of the human player.
B) it demands the human player of absolute exactitude.
C)it creates an exchange of errors between man and machine.
D)it is difficult to overcome psychological discomfort.
5.Kasparov’s remarks on his 1997 defeat imply that
A) man was no match to computer in intelligence.
B)Deep Blue was unbeatable.
C)Deep Blue also made blunders.
D)if he had made no blunders，he should have beaten Deep Blue.
标准答案： A,C,D,C,D
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