题目内容：

缺词填充

Have you heard such an old English saying? It says that we must go to b__1___ early and get up early. Then we should be h__2__ and clever.

This is t__3____ .The body must have enough sleep to be healthy .Children of teenagers(青少年) should have ten hours’ s___4_____ every night .If they don’t have e__5____ sleep, they can’t do their work very w__6____.

The body also needs e__7___. Walking, running, jumping, swimming and playing games are all exercise. Exercise keeps the body s___8__. Exercise also keeps the blood(血) moving around inside the body .It is very i__9__ because our blood takes food to all parts of our body. The h_10___ also needs blood, exercise helps us to think better!