Modal Verbs of Ability and Permission Exercise

Look at the following phrases and write in which type you think it is. Then use one of the modal verbs in brackets to fill the gaps. 1  _______ You (may/could)________________ leave now if you wish. 2 _______ (Could/May)________________ you open the window a bit, please? 3 _______ (May/Can)________________ you play the piano? 4 _______ Listen, please. You (may not/could not)________________  speak during this exam. 5 _______ You (can't/might not)________________ smoke on the bus. 6 _______ (Can't/May)________________  I make a call on your mobile? 7 _______ Do you know if Mark (can/may)________________ sing? 8 _______ (Can't/May)________________ I sit here, please? 9 _______ Caroline, your friends (can/could)________________ stay the night if they want to. They're perfectly welcome. 10 _______ I'm sorry but you (can't/may)________________ use the computer until after I've finished. 11 _______ (May/Could)________________ you lend me 40 Euros til Monday? 12 _______ Listen, please. Students (may/could)________________ study in the library from five to nine in the evening.