用括号内所给单词的适当形式填空。

1. We should often exercise to stay _____ (health).

2. Sam says, "Mary is _____ (heavy) than me".

3. I can't go to school, I have to rest today, because I have a _____ (head).

4. We go to the movies _____ (one) a month.

5. Chinese medicine is now popular in many _____  (west) countries.

接力器的运动速度能在一定范围内调整的目的是为了满足（）的要求。

A.调保计算；

B.增减负荷；

C.无差调节；

D.以上都不正确。