MUST/HAVE TO/SHOULD- INTERACTION

MUST+ INFINITIVE VERB. For example: I must get up at 5 tomorrow

HAVE TO+ INFINITIVE VERB. For example: I have to start work early

SHOULD+ INFINITIVE VERB. For example: You should do your work properly

MUSTN'T+INFINITVE VERB. For example: You mustn't do that!

DON'T HAVE TO. For example: You don't have to worry

SHOULDN'T+ INFINITIVE VERB. For example: You shouldn't smoke here

MUST+SUBJECT+INFINITIVE VERB. For example: Must you go so early?

DO/DOES+SUBJECT+HAVE TO+INFINITIVE VERB. For example: Do you have to go so early?

SHOULD+ SUBJECT+INFINITIVE VERB. For example: Should you go quickly?

We use MUST and HAVE TO to talk about obligations. These things are necessary or important. MUST is often used for a personal obligation (something we have decided for ourselves that we must do). For example: We must give up eating chocolates

MUST is also used in written rules. For example: All applicants must provide proof of identity

HAVE TO is used for external obligation. For example:We have to wear uniforms (It's a company rule)

SHOULD indicates obligation in the sense of duty or correctness, often when criticizing another person. For example: You should be at work now