6．Scientists can learn about man by studying animals，such as mice，rats and monkeys．The scientists in a laboratory are experimenting on mice and they are studying the relationship between diet and health．
In this experiment，the scientists are studying the relationship between the amount of food the mice can eat and their health．The mice are in three groups．All these groups are receiving the same healthy diet．But the amount of food that each group is receiving is different．The first group is eating one cup of food each day，the second two cups，and the third three cups．
After three years，the healthiest group is the one that is only eating one cup of food each day．The mice in this group are thinner than normal mice but they are more active．Most of the day，they are running，playing with one another，and using the equipment in their cages．Also，they are living longer．Mice usually live for two years，while most of the mice in this group are still alive after three years．
The second group of mice is of normal weight．They are healthy，too．They are active，but not as active as the thinner mice．But they are only living about two years．
The last group of mice is receiving more food than the other two groups．Most of the day，these mice are eating or sleeping．They are not active．These mice are living longer than the scientists thought-about a year and a half，but they are not healthy．They are sick more often than the other two groups．
55．The first group is the thinnest mainly becauseB．
A．they run and play all day long
B．they eat only one cup of food a day
C．they live longer than the other groups
D．they are bored with the kind of food in the cup
56．How long do normal mice live according to the passage？C
A．About one year．B．About a year and a half．
C．About two years．D．About three years．
57．What can we learn from the experiment？A
A．Daily amount of food may influence our health．
B．Sleeping may have nothing to do with weight．
C．Playing with others may help us sleep better．
D．Less exercise may make us live longer．
58．This passage is mainly about the relationship betweenC．
A．sleep and weight B．exercise and equipment
C．food and health D．weight and exercise．
分析 本文是一篇科教类阅读，主要介绍了一项在老鼠身上进行的"饮食与健康之间的关系"的试验结果．
解答 55-58．BCAC
55题答案：B考查细节推理，根据文章第三段的After three years，the healthiest group is the one that is only eating one cup of food each day．The mice in this group are thinner than normal mice but they are more active．三年后最健康的一组是每天只吃一杯食物的．这一组的老鼠比正常老鼠瘦但是更加活跃．可知老鼠瘦的主要原因是"因为它们每天只吃一杯食物"，故本题答案为B选项．
56题答案：C考查细节推理，根据倒数第二段的The second group of mice is of normal weight…But they are only living about two years．（第二组老鼠的体重是正常的…但是他们只能活两年）可知本题答案为C选项．
57题答案：A考查推理判断，试验对老鼠进行的是日常饮食量的控制，结果表明饮食量不仅对体重有影响而且也对寿命有影响；故本题答案为A选项"每天的食物摄入量可能会影响到我们的健康"．
58题答案：C考查细节推理，根据第一段的…they are studying the relationship between diet and health．（他们正在研究饮食与健康之间的关系）可知本题答案为C选项．
点评 本文是一篇科教类阅读，题目涉及多道细节理解题，做题时结合原文和题目有针对 性找出相关语句进行仔细分析，结合选项选出正确答案．推理判断也是要在抓住关键句子的基础上合理的分析才能得出正确的答案．
