A gym receptionist is explaining the membership rules to a new member. Choose the correct option for each blank.
"Welcome! You _________________________ show your membership card every time you enter the gym — it's our security policy. You _________________________ bring your own towel because we provide fresh ones for free. One more thing: you _________________________ use your phone in the weight room. It distracts other members and could cause accidents!"
The correct answers are have to, don't have to, and must not.
Have to expresses an external obligation — the gym requires you to show your card. Don't have to means bringing a towel is not necessary because the gym provides them. Must not expresses a prohibition — using your phone in the weight room is forbidden because it is dangerous and distracting. Note the key difference: don't have to means "it's not necessary," while must not means "it is not allowed."