Lesson 112 of 126

The lesson

11.7 ~に違いない — Must Be

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Overview

Learn ~に違いない (にちがいない), used to express strong certainty about a conclusion. It is stronger than ~はずだ and closer to "I'm sure that ~" or "it must be ~".

Formation

Plain form + に違いない

FormExample
Verb知っているに違いない
い-adjective高いに違いない
な-adjective好きに違いない
Noun先生に違いない

Note: For な-adjectives and nouns, the だ copula is dropped before に違いない.

Strength of certainty

~に違いない is stronger than ~はずだ or ~と思う:

ExpressionCertainty level
~かもしれないmaybe (low)
~と思うI think (moderate)
~はずだshould be (reasoned)
~に違いないmust be (strong certainty)

In writing

違いない is fairly strong and can sound assertive. In writing and formal contexts it is common. In casual speech, people might soften it or use ~はずだ instead.

Dialogue

A: That shop is always crowded. B: It must be delicious.

A: Tanaka-san looks busy lately. B: There must be a new project.

A: That bag looks really expensive. B: It must cost over 100,000 yen.

New words

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