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There is an old saying: Early to bed, early to rise, makes a man healthy, wealthy and wise. It means that we should go to bed early and get up early the next morning. By doing this, we will be in good health. And we'll also be rich and clever.
It's true that our bodies need to have enough sleep to be healthy. Children should have a ten-hour sleep every night. Those who do not have enough sleep can't do their work very well. They will not be clever and they may not get wealthy in the future.
The body needs exercise as well. Walking, running, jumping, riding bikes and playing games are all exercise. Exercise helps to keep the body strong and fit. It also helps the blood(血液)to move around inside the body. The head needs blood too. So exercise helps people think better.
