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?

HFC应用 (45) 传输技术，综合接入多种业务。HFC的用户端从PC机接收的以太帧被封装在时隙中，经过 (46) 调制后，通过HFC网络的上行数据通路传送给CMTS。

45（）

A．模拟

B．模拟和数字

C．数字

D．基带