の+じゃなかった? Vs の+ じゃない? Tenses used


For example:

> 授業があるんじゃなかったの?
>
> 授業があったんじゃなかったの?
>
> 授業があるんじゃない?
>
> 授業があったんじゃない(の)?

Are they the same? If yes, which are more common? Basically what are the
differences?




I think じゃない and じゃなかった are the same for this case.




授業があるんじゃなかったの？ means "you would attend the class, wouldn't you?", in other
words, it expresses that you thought someone was going to have the class but
have found something paradoxical and suspect that.

授業が あったんじゃないの{HLLLLLHLH}？ or …じゃなぃい{LLHLH}？ means that you though someone had
the class but have found something paradoxical and suspect that.

授業があったん じゃないの{HHHLH}？ or …じゃない{LLLH}？ means that you guess someone had a
class.

