How to use 不是不
Subject + 不是 + 不 / 没 + Predicate; Subject + 不 + Modal + 不 / 没 + Predicate
Two negatives can work together to reject a negative claim or make an affirmative conclusion more emphatic. 不是不 says that the explanation is not a lack of the quality or action in question. A following clause often supplies the real explanation. With a modal, the outer negative changes necessity or possibility before the inner negative describes the action.
Read each layer separately rather than assuming all double negatives mean exactly the same thing. 不可能不 excludes the possibility of nonoccurrence, while 不能不 often presents action as necessary. A pattern denying that any single person lacks a quality applies that quality to everyone in the relevant group. Scope determines both the strength and meaning of the statement.
Examples with pinyin and English
他不会不来的。
There is no way he's not coming.
她不可能不知道。
There is no way she doesn't know about this.
她太害羞了， 不是不礼貌。
She's too shy; It's not that she's not polite.
他不是没有钱，是不想乱花钱。
It's not that he doesn't have money; it's just he doesn't want to spend it recklessly.
What to remember
- Interpret the scope of each negative.
- 不是不 often introduces a correction.
- 不能不 commonly expresses an unavoidable action.
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Source and editorial notes
Explanation rewritten for Laowai. Examples are adapted from the Laowai English grammar curriculum, with editorial corrections where needed. The original curriculum credits AllSet Learning’s Chinese Grammar Wiki as used with permission. Read the retained source credits.
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