1. 表示有责任或义务做某事，其后可接 to do sth 或 of doing sth。如：
A man has a duty to earn money for his family. 男人有挣钱养家的责任。
Every citizen has the duty of defending his country. 每个公民都有保卫祖国的责任。
2. 表示责任义务，视含义的具体或抽象可用作可数或不可数名词。如：
Everyone has a duty to his country. 为国效劳，人人有责。
He did it out of a sense of duty. 他做此事是出于一种责任感。
表示作为工作一部分的职责或职务等，通常用复数形式。如：
Dont forget your duties as a soldier. 不要忘记你作为一名战士的职责。
Your duties include checking the post and distributing it. 你的职责是检查和发送邮件。
3. 比较 do duty for sb(代替某人)与 do duty for sth(充当或当作某物用)。如：
He did duty for a sick comrade. 他接替一位患病的同志工作。
An old wooden box did duty for a table. 一个旧木箱子被当作桌子用。
4. 用于 on (off) duty, 意为值(值)班当(不当)班等(注意不用冠词)。如：
He goes on duty at 8 am and comes off duty at 5 pm. 他上午8点上班下午5点下班。
The rule is that someone must be on duty at all times. 按照规定，任何时候均需有人值班。下载本文
