It is my duty to report it to the police.

把这事报告给警方是我的责任。

《牛津词典》

It is my duty to rescue them.

我的职责就是去营救他们。

youdao

It is my duty to help you.

帮助你是我的义务。

youdao

But although my duty is clear, it is in some way painful.

VOA: special.2009.10.08

Now, I think it's important that as governor, that I understand - my constitutional duty is to be the governor for all the people of my state.

NPR: Florida Weighs Options After Breaking Party Rules

As one whose duty it is to ensure children are protected from abuse, I would caution my European colleagues to study these issues intensely before adopting their own wide-ranging registries.

ECONOMIST: Protecting children