I can't / have to ride a bike. I always fall off.
CAN'T (Ability)
Remember, you are in a library. You musn't / don't have to speak loudly.
MUSTN'T (prohibition)
You can / must have friends over to stay, Millie.
CAN (permission)
In England you can / must drive on the left.
MUST (obligation)
There's plenty of time. You mustn't / don't have to hurry.
DON'T HAVE TO (no obligation)
We mustn't / don't have to go to school tomorrow. It's Sunday.
DON'T HAVE TO (no obligation)
I must / mustn't leave now. I don't want to be late
MUST (obligation)
You must / mustn't touch that wire. It's dangerous.
MUSTN'T (prohibition)
Hillary has lived in Spain more than 20 years. She can / has to speak Spanish fluently.
CAN (ability)
Can / Must I open the window, please?
CAN (permission)