Ex. 3 Open the brackets and use the proper infinitive after the verb must.
1. Look! All people in the street are going with their umbrellas up. It must (be raining).
2. He has changed his job. He must (have followed) your advice.
3. He must (have fallen) ill. Otherwise he would have come to the party.
4. Where is Michael? He must (be) here by now. – He lives in the country. He must (have missed) the train.
5. What a dreadful noise! What is the matter? – Our neignbours must (be quarrelling) again.
6. Nobody must (have noticed) that he was not used to speaking in public.
7. The criminal must (have been) very careful. He did not leave any fingerprints.
8. We are late, I am afraid. Ann must (be waiting) for us.
9. He must (have forgotten) that he promised to come.
10. They must (have been writing) a composition for two hours. They must (be) tired.
11. You must (have misunderstood) me, I did not want to hurt your feelings.
12. Nobody must (have seen) him enter.
13. I hear someone’s steps outside. She must (be going).
14. You may find him in the garden. He must (be reading).
15. It is impossible to change anything. One must (take) things as they are.