Trees are useful to man in three important ways.
The first important way is that they provide(提供) man with food, wood and the other products. Trees provide not only man with food, but also many animals with food. Without trees many animals could not live on the earth. It’s not easy for man to live on the earth, either.
The second important way is that trees give us shade(阴凉). On a hot summer day, people are eager(渴望) to have a rest under the tree after they have a long walk. You can imagine how important the shade of a tree is to man and animals.
The third important way is that trees help to prevent droughts and floods(防止干旱和洪水). However, in many parts of the world, man hasn’t realized the third way. They were cutting trees down in large numbers. In the end they find that they have lost the best friends they had.
根据短文内容，回答下列问题。
How many important ways are trees useful to man?
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Trees only provide man with food, don’t they?
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On a hot summer day, what do trees give us?
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What does the underlined word “they” means？
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What’s the best title of the passage?
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