You can go now. (you're allowed to - permission) • You can't leave the room. (you aren't allowed to) • Can/May I have some more tea? (Is it OK for me to ...? - asking for permission) Can I help you with the dishes? (Would you like me ... - offer) • Could I have some milk? (Is it possible that ...? - asking for permission) • He may/might come. (It's possible ... - possibility) • You should/ought to be careful what you eat. (It's my advice.)