Don't . Listen carefully in class.

I like doing sports, because it us.

—It is harmful, so people must keep away from it.

    Trees are an important part of the Earth. They provide wood for buildings and things for making paper. They provide homes for all kinds of insects(昆虫),birds and other animals. For example, many birds live in trees. Many kinds of fruits come from trees, such as apples, oranges, pears and peaches.

    Trees also help keep our air clean and our ecosystems(生态系统)healthy. We breathe in oxygen and breathe out harmful gases. However, trees breathe in harmful gases and breathe out oxygen. And trees can help other plants grow because they can hold the soil. Trees keep the soil from being blown away, so plants can fight against strong winds.

    Trees do lots for us, our environment and other plants and animals, but we don't just love trees for that. Trees can also be very beautiful and we can enjoy the beauty of them.

1）树木对人类很重要。

2）列举两三条树木对人类重要的原因，如提供氧气、净化空气等。

3）为了地球和人类的未来，请遵守法律，保护树木，植树护林。