Activity modal verbs

Intermediate Level
Can, Could, May and Might
Use one of the modal verbs in brackets to fill each gap.
1 They (can/might)________________ be away for the weekend but I'm not sure.
2 You (may/might)________________ leave now if you wish.
3 (Could/May)________________ you open the window a bit, please?
4 He (can/could)________________ be from Sheffield, judging by his accent.
5 (May/Can)________________ you swim?
6 Listen, please. You (may not/might not)________________ speak during this exam.
7 They (can't/may not)________________ still be out!
8 You (couldn't/might not)________________ smoke on the bus.
9 With luck, tomorrow (can/could)________________ be a cooler day.
10 You (can/might)________________ be right but I'm going back to check the times.