题目内容：

阅读理解。

Scientists are trying to make the deserts into good land again.They want to bring water to the deserts so that people can live and grow food there.They are learning a lot about the deserts,but more and more of the earth is becoming deserts all the time.Scientists may not be able to change the desert in time.

Why is more and more land becoming deserts?Scientists think that people make deserts.People are doing bad things to the earth.For example,scientists tell the people how important plants are for stopping land becoming desert,but people don’t pay enough attention to the green plants.

Some places on the earth don’t get much rain.But they still don’t become deserts.This is because some green plants are growing there.Small green plants and grass are very important to dry places.Plants don’t let the sun make the earth even drier.Plants don’t let the wind blow the soil away.When a bit of rain falls,the plants hold the water.Without plants,the land can become desert more easily.The present fact is that green plants on the earth are fewer and fewer.If there were no green plants on the earth,the whole earth would become desert.

1.Deserts    .

A.never have any plants or animals in them before

B.can all be turned into good land soon

C.have little water or plants

D.make the earth drier

2.Small green plants are very important to dry places because    .

A.they don’t let the sun make the earth into good land

B.they don’t let the wind blow soil away

C.they are green

D.they have leaves

3.After reading this,we learn that    .

A.plants can keep dry land from becoming deserts

B.it is good to get rid of the grass in the deserts

C.all places without much rain will become deserts

D.it is better for the dry land to grow grass than to grow trees