Scientists can learn about man by studying animals, 阅读理解答案

　　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.

　　32．The first group is the thinnest mainly because ________.

　　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

　　33．How long do normal nice live according to the passage?

　　A. About one year . B. About a year and a half.

　　C. About two years. D. About three years.

　　34．What can we learn from the experiment?

　　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.

　　35．This passage is mainly about the relationship between _________.

　　A. sleep and weight B. exercise and equipment

　　C. food and health D. weight and exercise

　　BCAC