Have to, must, don't have to, must not
Have to and must are used to indicate a rule or an obligation. They have almost the same meaning. Have to is often used to indicate the obligation comes from outside, eg I have to lose weight (the doctor told me). Must often shows an internal feeling, eg I must call my mother tonight.
Don't have to and must not (mustn't) are very different. Don't have to shows a lack of obligation / no rule eg you don't have to carry your umbrella when it rains (but you can if you want to). Mustn't indicates prohibition, the existence of a rule saying don't, eg you mustn't chew gum in class (if you do there will be some consequence).
Can shows permission, that something is
possible or allowed. eg People in England can
drink alcohol when they're 18.
You _________________ have a licence
to drive a car.
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