Forests have always been useful and impo

题目：

　　Forests have always been useful and important to man who makes use of them in many ways. Every day trees are serving man everywhere. Trees supply man with fruits and building materials in the form of wood. Without trees it would be impossible to build houses, boats, bridges and so on. Furniture such as desks, chairs and beds is made of wood. Trees can stop man from terrible heat. They're also useful in preventing good and rich top soil from being washed away during heavy rains.

　　If there were no trees, heavy rains would wash away the rich top soil that is so important to plants. The result is that the land will become a desert. There are plenty of desert areas in the world. A long time ago these desert areas used to be very rich areas, but man in the past had no enough knowledge about science of nature, they cut down too many trees in the area where they lived and never planted new ones. By and by the rich top soil was blown and washed away by strong winds and heavy rains. In the end the rich land changed into useless deserts where nothing could grow.

小题1:According to the passage, ______.

A．a long time ago, man didn't know how to make use of wood

B．trees are not as useful as they were in the past

C．trees were more found in the past than they are today

D．people have always found trees useful　　小题2:If there were no trees, ______.

A．the land would become better

B．heavy rains would be very clean

C．the rich soil couldn't be kept

D．there wouldn't be any plants　小题3:From the passage, we know that man must ______.

A．do nothing to keep the balance（平衡）of nature

B．take his best to keep the balance of nature

C．try his best to keep the balance of nature

D．do his best to stop the balance of nature