题目内容：

阅读短文，根据要求完成文后的题目。

Exercise is good for you because it can help you to keep fit and healthy. It is not enough just to eat a healthy diet. Exercise is important too. Exercise will make your muscles (肌肉)stronger. There are about 600 muscles in the body. They move your bones and let you move your joints（关节）. If you do not exercise your muscles, they will be weaker and smaller. One of the most important muscles in the body is the heart. To exercise your heart, you need to do something like swimming, or playing a game in which you run about. This will make you breathe more deeply and make your heart and lungs stronger. One of the places where you can exercise is at school. At school, children have PE lessons that help them to keep fit and well. Try to exercise at least three times a week because exercise is good for you!

1.How many muscles are there in the body?

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2.What can we do to exercise our heart?

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3.Why is school one of the places where children can exercise?

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4.请将文中画线句子翻译成汉语.

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5.请给短文拟一个适当的英文标题.

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