12．In a time when a dangerous number of people are overweight，many people seem to have forgotten the most important way to keep healthy and slim---exercise．And as a new study carried out on mice in the lab has shown，exercise done early in life can rward you in your adult years．
A team of researchers at the University of California studied the effects of early exercise on adult physical activity，body mass and eating．They found that early-age exercise in mice has positive effects on adult levels of voluntary exercise in addition to reducing body mass．
"These results may have an effect on the importance of regular physical education in elementary and middle schools，"said Theodore Garland，a professor of biology，who led the research project．"If kids exercise regularly through their school years，then they may be more likely to exercise as adults，which could have far-reaching poitive effects on human health and well-being．"
Although the positive effects of early-life exercise lasted for only one week，it is important to note that one week in the life of a mouse is the same as about nine months for humans．"Our results suggest that any positive effects of early-life exercise on adult eercise will need to be kept up if they are to be long-lasting．"
His team of researchers found，too，that all mice that had access to early exercise were lighter in weight than non-exercised mice．
Garland explained that，in general，exercise will stimulate appetite sooner or later．However，it is possible that certain types of exercise，done for certain periods of time or at certain light levels，might not stimulate appetite much，if at all，at least in some individuals．
"If we could understand what sorts of exercise these might be，then we might be able to tailor exercise recommendations in a way that would bring the benefits of exercise without increase in appetite，leading to a better chance of weight loss，"he said．
28．How long do the positive effects of early-life exercise last for a mouse？B
A．One day B．One week C．One month D．Nine months
29． Which of the following statements is TRUE according to the article？A
A．More study is needed to better understand the effects of different types of exercise．
B．Early-life exercise has life-long positive effects on people
C．Kids should be encouraged to o exercise as early as possible to ensure physical health．
D．The new study on mice mainly focused on how exercise affects appetite．
30．The underlined word"stimulate"in the last but one paragraph is closest in meaning toB．
A．decline B．improve C．vary D．harm
31．What is the article mainly about？D
A．New ways to fight against being overweight．
B．The positive effects of mice
C．The possible risks of doing exercise
D．The positive effects of early-life exercise．
分析 本文属于说明文阅读，作者通过这篇文章向我们介绍了在生命的早期锻炼可以帮助你在成年后获得健康的生活，并通过用小白鼠实验证明了这个观点，因此作者提倡我们多进行锻炼，保持自己身体的健康．
解答 28．B 细节理解题，根据第四段Although the positive effects of early-life exercise lasted for only one week，it is important to note that one week in the life of a mouse is the same as about nine months for humans．虽然早期的正面效果只能持续一个星期，可知小老鼠的早期锻炼能持续一个星期，故选B．
29．A 推断判断题．根据第七段："If we could understand what sorts of exercise these might be，then we might be able to tailor exercise recommendations in a way that would bring the benefits of exercise without increase in appetite，leading to a better chance of weight loss，"如果我们能研究出这些锻炼形式都有哪些，或许我们可以给人们量身定做一些锻炼建议，这样可以带来如期的锻炼效果而不会增加胃口，从而达到减肥的效果，可知我们的研究还没有到位，故选A．
30．B 词义猜测题，根据第六段However，it is possible that certain types of exercise，done for certain periods of time or at certain light levels，might not stimulate appetite much，if at all，at least in some individuals．可知有可能一些锻炼形式对某些个体来说不会那么刺激人的胃口，故选B．
31．D 主旨大意题，通读全文可知本文主要向我们介绍了早期生活锻炼的积极影响，故选D．
点评 考查学生的细节理解和推理判断能力．做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确选择．在做推理判断题时不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
