1
general::
must do something
used when saying that it is very important that someone does something, because someone in authority or a rule says this, or because of the situation:
• You must be home by midnight. • He must not smoke in here. • I must remember to call her.
have to do something
to need to do something because it is necessary or important:
• I have to go home early. • She has to talk to him first.
be obliged to do something
especially British English to have to do something, because of a legal, professional, or social rule:
• Members of parliament are obliged to declare all their financial interests.
be required to do something
( also be obliged to do something especially American English ) formal to have to do something – used especially in written notices and official documents:
• New students are required to register with a doctor.
have an obligation to do something
( also be under an obligated to do something ) to have to do something because it is the duty of someone in your position to do it, or because you have officially agreed to do it:
• The landlord is under an obligation to keep the building in good repair.
be forced/compelled to do something
to have to do something that you do not want to do, because you are in a situation that makes it impossible to avoid:
• She was forced to retire early due to ill health.
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