What is compulsory English?

Obligation in English is: obligation.

obligation　English [?bl?'ɡe?n] American [?ɑ?bl?'ɡe?n]n. Obligation; responsibility.

We are invited, but we are under no obligation to go. We are invited, but it does not mean we are under no obligation to go.

I have an obligation to keep secret for the taxpayer.

Analysis: nouns such as duty, obligation, responsibility and function all mean "obligation" or "responsibility".

Duty refers to the obligations that a person must always fulfill according to moral and legal standards, emphasizing consciousness.

Obligation refers to moral or legal obligations to others, emphasizing mandatory.

It also refers to some kind of obligation that is forced to be performed due to making a promise.

Responsibility refers to any duty, responsibility, responsibility or duty owed to one's position, emphasizing responsibility for others.

Function refers to performing a certain duty due to a position or professional relationship.