1. 阅读短文，选择正确的答案。

    We know the air is very important for us. Without air, we couldn't live. Other creatures can't live either. We need clean air. The dirty air is bad for us. Now the air pollution is very serious in some places. For example, the smoke from some factories make the air dirty. Exhaust gas from cars make the air dirty. The forest fire can make the air dirty, too. So we need to pay attention to the air pollution. We can plant more trees and think of other ways to sovle the problem.

1. （1） Is the air very important for us?

   A . Yes, it does. B . Yes, it is. C . No, it isn't.
3. （2） What will become of us without air?

   A . We can live. B . We can't live. C . We can breathe.
5. （3） What can make the air dirty?

   A . The smoke. B . The trees. C . The grasses.
7. （4） Is the air pollution very serious in some places?

   A . Yes, it is't. B . No, it isn't. C . Yes, it is.
9. （5） What should we do to keep the air clean?

   A . Do more exercises. B . Eat more vegetables. C . Plant more trees.