欠國家的那一份（稅）
同樣是「欠著、該交」，只是交的對象換成國家、交的東西是錢：買某樣東西（尤其進口貨）時，依規定該繳給國庫的那一筆。這支從字根「該還的」直接長出，歷史上很早就有。
duty (tax on goods) · noun · B1
A tax you pay on something you buy, especially something brought in from another country.
關稅 / 稅
核心畫面
You can picture duty as 'what is owed' — something that falls on you and is expected from your side: the thing you are on the hook for, whether because it is right, because of your job, or because a rule places it on you.
可以想成 duty 是「該還、該盡的那一份」——落在你頭上、別人有理由期待你交出來的東西。不論是因為這樣做才對、因為…更多收起
可以想成 duty 是「該還、該盡的那一份」——落在你頭上、別人有理由期待你交出來的東西。不論是因為這樣做才對、因為這是你的工作、還是因為規定壓在你身上，那份「輪到你、由你來扛」的東西就是 duty。From the word’s history
From Old French deu 'due, owed' (the source of English 'due'), ultimately from Latin debere 'to owe'. The root sense is literally 'what is owed', which is exactly the thread running through every modern sense.
源自古法文 deu「應得的、欠著的」（也是英文 due 的來源），再往上是拉丁文 debere「欠」。字根的意思就是「欠著、該交的」，這條線正好串起下面每一個用法。
etymonline.com/word/duty
From the picture
頂替著用（充當）
把「該盡的職責」幽默地搬到物品上：一樣東西被派去扛起某個本來不是它的工作，就像它也在「上工盡責」。靠 do duty as 這個片語帶出來。
do duty as something · noun · B1
In the phrase 'do duty as something': to be used as something, often something it was not first made for.
充當 / 兼作
Also in this word
duty (moral obligation) · noun · B1
Something you have to do because it is the right thing to do, or because a rule says you must.
義務 / 本分
duty (task from your job) · noun · B1
A task your job or position places on you.
職責 / 職務
原始詞典資料8 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
Dutyname
- 1
A surname.
dutynoun/ˈdjuː.ti/
- 1
That which one is morally or legally obligated to do.
- Do your duty by me! -No, we don't have a duty to keep you abreast.
- 1805, 21 October, Horatio Nelson England expects that every man will do his duty.
- 2
The state of being at work and responsible for or doing a particular task.
- I’m on duty from 6 pm to 6 am.
- 3
An excise tax; especially, one on imports or exports.
- customs duty
- 4
obsoleteOne's due, something one is owed; a debt or fee.
- Take that which is thy duty, and goo thy waye.
- 5
obsoleteRespect; reverence; regard; act of respect; homage.
- my duty to you
- It [the letter] was written with a plain, unaffected, homely piety that I knew to be genuine, and ended with ‘my duty to my ever darling’—meaning myself.
- 6
engineeringnatural-sciencesphysical-sciencesThe efficiency of an engine in work done per unit of fuel; particularly, the number of pounds of water which a steam pumping engine can raise one foot by burning one bushel or hundredweight of coal.
- 7
The act of urination or defecation, especially for a dog.
- The basic idea in housebreaking is not to wait until the puppy sins and then punish him; it is to call nature to your aid and thus make it easy for him to do his duty.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。