- 1僅限必要知悉、有必要才告知（台灣常整句留英文：on a need-to-know basis）
If information is given on a need-to-know basis, people hear only the piece they must have, at the moment they must have it — and nothing extra. Offices, armies, hospitals, and police work use this a lot. It is not a warm way of sharing; it is a tight way, used when someone decides that extra facts would not help, or might even do harm. You almost always meet the whole phrase on a need-to-know basis, not the word standing alone. Though actually, people also stretch it: “That’s need-to-know” can simply mean “I am not going to tell you.” The matter: need-to-know is one idea, not three loose words.
「need-to-know」常以「on a need-to-know basis」這個整句出現，指資訊只給必須知道的部分，而且只在必須知道的時候給，多的一樣都不給。辦公室、軍隊、醫院和警察工作常用它。這不是溫和分享的方式，而是收得很緊的方式，用在有人判斷多出來的資訊沒有幫助，甚至可能造成傷害的時候。
幾乎都是整句一起出現，很少單獨用這個詞。有人也會把「That's need-to-know」直接當作「我不會告訴你」來說。連字號很重要，need-to-know 是一個概念，不是三個零散的字。
組成need + to + know: only what you need, when you need to know it.
原始詞典資料2 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，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。
need-to-knowadj
- 1
(of information) given to another only when necessary.
- 10 to 2 a.m., X, Yogi DMT and a box of Krispy Kremes In my need-to-know post just outside of Area 51 Contemplating the whole "Chosen People" thingy When just a flaming stealth banana split the sky Like one would hope, but never really expect to see in a place like this
need-to-knownoun
- 1
Something that one needs to know; a piece of necessary information.
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。