Read the following passage and mark the letter A, B,C or D to indicate the correct answer to each of the questions. Scientists are trying to make the deserts into good land again. They want to bring water to the deserts, so people can live and grow foods. They are learning a lot about the deserts. But more and more of the earth is becoming deserts all the time. Scientists may not change the desert in time. Why is more and more land becoming deserts? Scientists think that people make deserts. ...

Read the following passage and mark the letter A, B,C or D to indicate the correct answer to each of the questions.

Scientists are trying to make the deserts into good land again. They want to bring water to the deserts, so people can live and grow foods. They are learning a lot about the deserts. But more and more of the earth is becoming deserts all the time. Scientists may not 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.

Some places on the earth don’t have very 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 hot sun make the earth even drier. Plants don’t let the wind blow the soil away. When a little rain falls, the plants hold the water. Without plants, the land can become a desert much more easily.

According to the passage, deserts _______.