じゃないが => It's not that... but... N4
How to say the beginning
んじゃない => can not, impossible to... N4
Ban
じゃないか => right? isn't it? let's~; confirmation N4
Speculation
じゃないか / ではないか => right? isn't it? N3
Confirm
んじゃないか => right? isn't it? let's~; confirmation N4
Confirm
じゃないか / ではないか => right?; isn't it? (Criticism) N3
Criticize
んじゃ => If ... then... N4
Condition (hypothetical condition)
んじゃない => confirmation of information; express surprise towards listener N4
Speculation
じゃないか / ではないか => right? isn't it? let's~; confirmation N3
Surprised
んじゃなかったか => shouldn't have... N4
Regret
じゃない/ではない => to not be (am not; is not; are not) N5
じゃない => maybe; most likely; confirmation of information; express surprise towards listener N5
Emphasize negative meaning