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JLPT N4Expressions

ではないか / じゃないか— Isn't it? (rhetorical)

A rhetorical question or exclamation expressing realization, surprise, or a bid for agreement. The speaker asserts something they believe true and invites the listener to concur.

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Pro lessonUNIT 14 · EXPRESSIONS

Structure · 形

[Plain form] + ではないか (formal) / じゃないか (casual)

Examples · 例文

  • これは素晴らしいじゃないか！

    Kore wa subarashii ja nai ka!

    Isn't this wonderful!

    Exclamatory realization

  • もう時間じゃないか、急ごう！

    Mō jikan ja nai ka, isogō!

    Isn't it time already? Let's hurry!

    Realization + call to action

  • あの人は以前会ったことがあるんじゃないか。

    Ano hito wa izen atta koto ga aru n ja nai ka.

    Haven't we met that person before?

    Seeking a shared memory / agreement

Usage notes · 注意

  • Key Concept: ではないか = formal;
  • Note: じゃないか = casual.
  • Intonation matters: falling pitch = rhetorical assertion;
  • Detail: rising pitch = genuine question seeking agreement.
  • Embedded usage: 〜んじゃないかと思う = "I suspect / I kind of think..." (softened conjecture).

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ではないか is tested against.

vsじゃないですか (polite)

じゃないですか is the polite everyday version used to seek agreement or point something out. ではないか is more literary/emphatic and often masculine or dramatic in tone.

vsでしょう (right? / probably)

でしょう seeks confirmation of a probability the speaker is fairly sure of. ではないか carries stronger emotion — surprise, realization, or a rhetorical push toward a conclusion.

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