Must, might, may, could, can't to complete the sentences: 1. Where is David? He _________ (be) at school. It's 10 o'clock

1. Where is David? He could be at school. It\'s 10 o\'clock now and classes begin at 8.2. She might think that it is a good idea. It\'s crazy! 3. I\'m absolutely sure! They must arrive tomorrow, because I got a telegram.4. Are you joking! David can’t go to Paris next week. He doesn\'t have enough money. 5. They may live in New York, but I\'m not sure. 6. The concert must be wonderful tonight. Gergiev is a great conductor.