Раскройте скобки, употребляя тре¬бующуюся форму инфинитива.
1. Не knows mathematics much better than he did last year. He must (to work) a lot in summer. 2. Your mathematics is very poor. You must (to work) at it in summer. 3. Where is Peter? — Oh, he must (to read) in the library. He is getting ready for a very difficult examination. 4. You must (to study) English for several years already. Your lan¬guage is very good. 5. Oh, look how white and clean everything is! It must (to snow) at night. 6. Oh, you are all in snow, you look like a snow¬man. It must (to snow) heavily. 7. Look, what huge snowdrifts there are everywhere, and the path is •covered with knee-deep snow. It must (to snow) for several hours already. 8. You look fresh! You must (to have) a good sleep at night. 9. You look very tired. You must (to have) a good sleep at night.
Не had to go — Ему пришлось
Не must have gone — Он, должно
уйти. быть, ушел.