完形填空（共15小题；每小题2分，满分30分）
阅读下面短文，掌握其大意，然后从21-35各题所给的四个选项中选出一个最佳答案。
Every person needs water and a diet of healthy foods. These foods should contain some fat, some fiber, a little salt and so on.
People need energy 21 . They eat different kinds of food which change into energy. The energy is 22 in calories(卡). Even when you 23, you are using energy – about 65 calories an hour. 24 you are at school, or walking home, your body is burning up 100 calories an hour. When playing football or basketball, you 25 be using 400 calories an hour. On Sports Day, during the relay race, you will use most of all, 26 as much as 650 calories an hour.
The Chinese diet is considered to be the healthiest in the world. It contains a lot of fruit and green vegetables. It is 27 in fiber and low in sugar and fat. The Chinese eat less sugar than many other countries in the world. That is 28 lots of people in China have healthy white teeth.
People in the Western world do not eat such healthy foods. They eat 29 fat and sugar and don’t take enough 30 . Because of this, they 31 weight very easily. Their diet contains a lot of 32 in the form of potato crisps, potato chips, butter, cream and chocolate. They eat a lot of sugar which exist in cakes, soft drinks, 33 and so on. The result is that many of them become fat. 34 some have bad teeth. In some parts of Britain, one person in ten, 35 the age of thirty, has no teeth left.
21. A. to sleep B. to live C. to eat D .to walk
22. A. measuring B. taken C. measured D. measure
23. A. are asleep B. have a dream C. have a rest D. go to bed
24. A. While B. During C. As D. If
25. A. must B. should C. need D. might
26. A. surely B. ever C. perhaps D. seldom
27. A. rich B. poor C. good D. bad
28. A. how B. why C. what D. that
29. A. much too B. many too C. too many D. too much
30. A. activities B. food C. work D. exercise
31. A. put on B. gain on C. get on D. put up
32. A. sugar B.fat C. salt D. fiber
33. A. sweets B. vegetables C. meat D. potato
34. A. But B. Or C. And D. As
35. A. during B. for C. with D. by
人造卫星绕地球做匀速圆周运动时处于完全失重状态，物体对支持面没有压力，所以在这种环境中已无法用天平称量物体的质量．针对这种环境，某兴趣小组通过查资料获知，：弹簧振子做简谐运动的周期为T=2π