Example: you must / don’t have to tidy your room. it’s a mess. 1 you don’t have to / mustn’t swim there. it’s dangerous. 2 i haven’t to / don’t have to do my homework. it’s saturday. 3 she must / mustn’t practise the piano tonight. she’s not very good. 4 they have to / don’t have to be home early. they’re very young. 5 we mustn’t / don’t have to buy tickets – entrance is free. 6 you can’t / must go to the party. it’s too late.