Choose the correct options to fill in the gaps

1. She [must|had] be taking a test.
2. Tom, [must|may] I ask you a question?
3. Children [can't|must] remain quiet in class.
4. He [might|had to] have forgotten about the meeting.
5. Sam, [will|might] you participate in the class discussion?
6. She [wasn't able|mightn't] to finish her test on time.
7. He [can't|didn't have] be at school yet.