Измените следующие предложения, употребляя сочетания must или may с Indefinite или Perfect Infinitive:
Образец:
He probably left his bag at home.
He must have left his bag at home.

It is possible that he knows her address.
He may know her address.

1. It is possible that he will return in May.
2. He probably lost his key on his way home.
3. It is possible that he left his note-book at his office.
4. The text is probably very difficult as he cannot translate it without a dictionary.
5. It is possible that it will rain to-morrow.
6. It is possible that he was a good singer once, but now he can't sing at all.

1. He may return ... .
2. He must have lost ... .
3. He may have left ... .
4. The text must be very difficult ... .
5. It may rain ... .
6. He may have been a good singer ... .