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!