阅读短文，然后根据其内容回答问题。

We should look after our trees

　　We should always remember to look after our trees as they are very important for our planet and in our lives．

　　First, trees keep the air clean because they give off the gas oxygen, which humans and animals need to breathe．They also take in other gases, like carbon dioxide, that we do not need．

　　Second, because the roots of trees hold the soil together they stop it from being washed away．In some parts of the world where a great many trees have been cut down, the land has been completely destroyed．

　　Trees provide homes for many different types of birds and animals, and they also supply their food．If trees are cut down, there will be no place for these birds and animals to live and nothing for them to eat．

　　In addition, trees often help in keeping us cool because they shade us from the hot sun．

　　Sometimes they also offer shelter(遮蔽)or protection from bad weather．

　　Finally, trees are beautiful to look at．The world would be a much uglier place if there were no trees．

　　All around the world forests are being cut down．We should look after the trees that are left and make sure that more are planted to replace those that have already been destroyed．

1．Why are trees important to animals and birds?

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2．Why might trees be very important in summer?

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3．What parts of trees do you think birds and animals eat?

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4．Write a sentence which sums up(总结)the argument．

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5．Number these statements in the order in which they appear in the argument．

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Trees keep us cool because they shade us from the hot sun．

Trees are beautiful to look at．

Trees keep the air clean as they give off oxygen and take in carbon dioxide．

Trees provide homes for birds and animals．

The roots of trees hold the soil together．