Duty refers to a moral or legal obligation; a responsibility.
Common usages include:
1. Duty as in "on duty" - meaning currently working or responsible
2. Duty as in "sense of duty" - moral obligation
3. Duty as in "import duty" - tax on imported goods
4. Duty as in "duty-free" - exempt from taxes
哎呦喂，duty这词儿可有意思了，说白了就是"责任"、"义务"那点儿事儿。
咱给您掰扯掰扯啊：
1. 值班/当班：比如"on duty"就是"在岗"的意思，医院里大夫护士老说的"我今儿值班"
2. 责任感：像"sense of duty"就是"责任感"，做人得有点儿担当不是？
3. 关税：这词儿在海关可常见了，"import duty"就是"进口税"，买东西得交钱
4. 免税："duty-free"就是"免税店"那个免税，出国旅游谁不去那儿扫货啊
补充说明：这词儿在法律文书里出现频率可高了，比如"fiduciary duty"翻译成"受托责任"，听着就专业。日常生活中说"do one's duty"就是"尽本分"的意思，咱中国人讲究这个。