be quiet
You must be quiet.
put litter in the garbage can.
You must put litter in the garbage can.
wash your hands.
You must wash your hands.
walk you dog here
You mustn't walk your dog here.
take photos here.
You mustn't take photos here.
swim here.
You mustn't swim here.
turn off your phone here.
You must turn off your phone here.
eat here.
You mustn't eat here.