3. I have seen the tiger since 1999. (变为一般疑问句)

________ ________ ________ the tiger since 1999?

2. The two boys are listening to the teacher in the classroom. (就划线部分提问)

________ ________ the two boys ________ in the classroom?

1. To keep our classroom clean is important. (用it改写句子)

________ ________ important ________ ________ our classroom clean.

10. It has an area of ______________ (超过) 20 hectare.

9. Jim wants ______________ (参加) the Birdwatching Club.

8. He is ______________ (对......感兴趣) watching TV.

7. It is ______________ (很重要的) to learn English well.

6. The man is ______________ (对我有敌意).

5. He is ______________ (够年龄) to go to school.

4. If we don't protect the birds, they will be ________ (处于危险中).