1. Where was Peter yesterday?.He must have been at school.The school started a week ago.
2. I'm absolutely sure! They must have arrived yesterday.I saw their tickets.
3. The course. may begin on the fifth of September but I'm not so certain aboit it.
4. Are you joking! Nick couldn't have gone to Moscow last week. He's supposed to be at work now.
5. They may have come from London, but I'm not sure.
6. We must have taken the wrong turn.We should be there by now.
7. They might have missed their train.Otherwise they wouldne be here by now.
8. It couldn't be Masha who answered the phone because she's away.
9. I can't find my cat anywhere.She couldn't have got out through the window.The opening is too small.