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39 The attitude of those concerned in the UK to the new rules proposed by ISU Can be best described as
A indifferent．
B reserved．
C enthusiastic．
D positive．

40 Which of the following is NOT true of the scoring system for diving?
A It is more biased．
B It is more reasonable．
C It is fairer．
D It is tighter．

第三篇
Eat More，Weigh Less，Live Longer
Clever genetic detective work may have found out the reason why a near。starvation diet
prolongs the life of many animals． ‘
Ronald Kahn at Harvard Medical School in Boston，US，and his colleagues have been able
to extend the lifespan(寿命)of mice by 18 per cent by blocking the rodent's(啮齿动物)
increase of fat in specific cells．This suggests that thinness--and hot necessarily diet--promotes long life in " calerie (热量卡) restricted" animals．
"It's very cool work．"says aging researcher Cynthia Kenyon of the University of California，San Francisco．"These mice eat all they want，lose weight and live longer．It's like heaven．"
Calorie restriction dramatically extends the lifespan of organisms as different as worms and rodents．Whether this works in humans is still unknown，partly because few people are willing to submit to such a strict diet．
But many researchers hope they will be able to trigger the same effect with a drug once
they understand how less food leads to a longer life．One theory is that eating less reduces the increase of harmful things that can damage cells．But Kahn's team wondered whether the
animals simply benefit by becoming thin．
To find out。they used biology tricks to disrupt the insulin(胰岛素)receptor(受体)gene in lab mice-_but only in their fat cells．"Since insulin is needed to help fat cells store fat，these animals were protected against becoming fat，"explains Kahn．
This slight genetic change in a single tissue had dramatic effects．By three months of age，Kahn，s modified mice had up to 70 per cent less body fat than normal control mice，despite the fact that they ate 55per cent more food per gram of body weight．
In addition，their lifespan increased．The average control mouse lived 753 days，while the thin rodents averaged a lifespan of 887 days．After three years，all the control mice had died，but one--quarter of the modified rodents were still alive．
"That they get these effects by just manipulating t11e fat cells is controversial，"says
Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and aging．
． But Guarente says Kahn has yet to prove that the same effect is responsible for increased
lifespan in calorie．restricted animals．"It might be the same effect or there might be two routes to long life，"he points out，"and that would be very interesting．"

41 Ronald Kahn and his colleagues can make mice live longer by
A offering them less food．
B giving them a balanced diet．
C disrupting the specific genes in their fat cells．
D preventing them growing larger

42 According to t11e passage，we d0 not know whether humans will benefit from taking in fewer calories partly because
A humans，worms and rodents are different．
B most people are not willing to be put on a strict diet．
C the effect is not known．
D genetic changes in tissues can not be 本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。