英语作文 树木是人类的好朋友，没有树木人们将不能生存，那么树木到底有什么作用

Trees are our good friends. They clean the air and bring us enough oxygen. They help keep the balance of nature. The green leaves and the different gestures of the trees add beauty to our city. With trees,many birds come to our city. They make our life vivid and interesting. We should protect the trees.Don't hurt our friends -- trees.

to beautify the living surroudings
to provide as much as possibe oxygen, the one necessity of life
to be carpened to the tools in everyday use
to hold water enough against flooding soil disasters
to back up the primitive time, the firsr barch of the tree used for clothes

不能教，自己想