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Lesson 250: Offering explanation with んです

んです is used to explain something, to show emphasis or to give reasoning.

We’ve already seen many examples of reporting something, for example さむいです(it’s cold). If we want to offer more of an explanation or show reasoning, we can add んです to the end of the sentence. The んです implies that there’s some background information or shared context/knowledge.

For example, compare these two sentences:

Observation/report Explanation
It’s hot.
It’s hot (so I’m not going out).
I have a cold.
I have a cold (so that’s why I look tired).

んですcan be used with affirmative, negative, present and past tense words. んです itself rarely changes tense. See the below table for examples of how to use んです with nouns, adjectives and verbs.

Present Past Negative
Noun みつなんです。
It's a secret.
It was a secret.
It's not a secret.
な-adjective しずかなんです。 しずかだったんです。 しずかじゃないんです。
い-adjective おもしろいんです。 おもしろかったんです。 おもしろくないんです。
Verb べるんです。 べたんです。 べないんです。

The formal version which is often used in writing is のです. In casual situations, んです can be shorted to んだ.

You can also use んです to seek explanation or confirmation in the form of a question. You might have heard the phrase どうしたんですか, which means what’s wrong? or what’s happened?. With んです here, you are acknowledging something about the context, e.g. the person you’re speaking to seems upset.

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