obliged

法律上必须

To be required by law.

被法律所要求。

法律规定

To be required by a legal statute.

被法律法规所要求。

道义上必须

To feel an ethical or moral duty to do something.

感到有道德或伦理责任去做某事。

A formal way to say 'thank you very much'.

To be required by the terms of a contract.

不得不；感激

Can mean either being forced to do something or feeling grateful.

可表示被迫做某事或心存感激。

觉得有义务

To feel a moral or social duty to do something.

感到有道义或社会责任去做某事。

感谢（某人）

Used to specify the person one is grateful to (e.g., obliged to you).

用于指明感激的对象（例如，感谢你）。

为...而感谢

Used to specify the reason for gratitude (e.g., obliged for your help).

用于说明感激的原因（例如，为你的帮助而感谢）。