根据短文内容，判断下列句子的正误，正确的用“T”，错误的用“F'。 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 food. They are learning a lot. about the deserts. But more and more of the earth is becoming desert all the time. Scientists may not be able to change the desert in time. Why is more and more land becoming desert? Scientists think that people make deserts. People are doing bad things to the earth. Some places on the earth don't get 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 dirt away. When a little bit of rain falls, the plants hold the water. Without plants, the land can become a desert much more easily. (     )1. Scientists are trying to change the deserts into good land. (     )2. Land is becoming desert little by little. (     )3. Scientists can change desert back into good land easily. (     )4. Small green plants need a lot of water. (     )5. Plants can keep dry land from becoming desert.