You use this to guess something softly. Or you use it to ask if your idea is right. It is like saying 'I think...' or 'Isn't it?'
Verb [dictionary form] + んじゃない？Primary
Verb [た-form] + んじゃない？
い-Adjective + んじゃない？
な-Adjective + な + んじゃない？
Noun + な + んじゃない？
You use this to guess something softly. Or you use it to ask if your idea is right. It is like saying 'I think...' or 'Isn't it?'
もうすぐ雨が降るんじゃない？
Don't you think it's going to rain soon?
あの映画、思ったより面白かったんじゃない？
That movie was more interesting than you expected, wasn't it?
彼はこの仕事、あまり好きじゃないんじゃない？
I get the feeling he doesn't really like this job, do you?
もしかして、鍵を部屋に忘れたんじゃない？
Could it be that you forgot your keys in the room?
このデータが間違っているんじゃないかと、私は思います。
I think that this data might be incorrect.
This phrase makes your idea sound gentle. It is like asking, "Don't you agree?" You are sharing a thought, not stating a fact. It helps everyone talk nicely together.
This is different from "~janai?". That asks for a simple yes or no answer. This is also different from "~jan". That is like saying "It is!" very strongly. This is also different from "~nja ne?". That is a rough way to say the same thing.
Watch out: When you use this with nouns or "na" adjectives, you must add "na" before "n ja nai?". For example, say "sensei NA n ja nai?" (Isn't he a teacher?). Do not say "sensei ja nai?". That means "Isn't he NOT a teacher?" It is a different meaning.
More formal alternatives(1)
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