2．
阅读短文，选择正确答案。
We have only one Earth. We get land(土地), air and water
from the Earth. We should take care of these things. We should keep them clean.
Farmers grow food on land. Food from dirty land is bad for us, so we should
keep the land clean. We can't build(建造) too many
houses. There isn't much land on Earth for farming. We should save it.
We all need water. We cannot live without water. We
drink and use it. But there is not much water in many places. In some places,
dirty water pollutes the rivers. Some people waste water. We should keep the
air clean too. We need fresh air to live.
