can, could, to be able to, to be allowed to
1. Mom, ..... you help me with my homework?
2. Did you know that Lisa ...... sing?
3. This ....... be right!
4. My father ........ believe his eyes! When he saw me....
5. My father says that I ........ (to go) out by myself next year...
6. We ...... to talk during the test.
7. I'm sick, but I think I ........ attend the meeting next week.