Modal Verbs of Probability Quiz

Use must, might, may, could or can't plus the correct form of the verb.

Where is David? He __________ (be) at school. Classes begin at 8. She __________  (think) that it is a good idea. It's crazy!
I'm absolutley sure!. They __________  (arrive) yesterday, I saw their ticket.
Courses __________ (begin) the fifth of September.
Are you joking! David __________ (go) to Paris last week. He doesn't have enough money.
They __________ (live) in New York, but I'm not sure.
The concert __________ (be) wonderful last night. Fiore is a great conductor.

Answer key:
must be - can't think - must have arrived - might/ may begin - can't have gone - could live - must have been

http://esl.about.com/library/grammar/blmodalprob.htm