А. Вставьте соответствующую форму инфинитива в следующие предложения:
Не speaks English well. Не must have studied it for a long time.
They are laughing. They must be having a good time.
1. Nobody answered the phone. They must out. (go)
2. The line is busy. He must ______ the phone, (use)
3. You made a long distance call. It must expensive. (be)
4. I need more money. I should my job. (change)
5. I got the wrong number. I may incorrectly. (dial)
6. What is he doing? He should ___ the report. (type)
7. Mr Smith didn't return my call. He might busy. (be)
8. I couldn't make my call. I must to put a coin at the slot. (forget)
9. There is somebody in the office. It might _______Miss Cooper, (be)
10. You've given me a letter. Shall I ______________ it? (send)
11. He is out. He must _______his dinner, (have)
12. There were five of them. It must _______ one of them.(be)

1) have gone

2) be using

3) have been

4) change

5) have dialed

6) be typing

7) have been

8) have forgotten

9) be

10) send

11) be having

12) have been