用所给动词的适当形式填空。

1. Look, they _______ (play) games on the playground.

2. Listen, who ________ (sing) in the next room?

3. — Why ______ (be) he very happy now? 

    — Because his mother gave him a present.

4. — Where _______ (be) you yesterday afternoon? 

    — I _______ (be) at home.

5. I _______ ( not do) my homework yesterday afternoon. I _______ (watch) TV.

6. — Who _______ (come) to see you last Sunday? 

    — My uncle _______ (do).

7. — _______ you _______ (play) football with your friends yesterday morning? 

    — Yes, I _______ (do).

8. _______ (go) and see who is in that room.

9. _______ (not play) in the street. It's dangerous.

10. _______ (be) there any ink in that bottle?

P＞MR，不在下列（）市场中

A.完全竞争市场

B.完全垄断市场

C.寡头垄断市场

D.垄断竞争市场