Is んですから/ので/... grammatically correct?


I've been told by my teachers not to use んです and から/ので together, but I
encounter them sometimes, both by sight and by ear. When I try to use it
myself, it's always marked wrong.

For example, I am quite sure the sentence 10時半のバスに乗るんだから、早く支度しなさい。in this
[link](https://www.jpf.go.jp/j/project/japanese/teach/tsushin/grammar/201009.html)
would be considered incorrect by my teacher, but it's stated to be correct
here.

jgram also states that [んです should never be used with other words/
constructions that also indicate reason, like
から、ので、ものですから](http://www.jgram.org/pages/viewOne.php?tagE=ndesu).

Which of the following are grammatically sound?

> んですから / んだから
>
> んですので / んだので
>
> んものですから / んものだから




> 「10時半{じはん}のバスに乗{の}るんだから、早{はや}く支度{したく}しなさい。」

This sentence would sound O.K. and even fairly natural, if not perfect, **if
it were uttered by a busy mom in an informal situation**. Grammarians might
disagree here, but it is something you would actually hear native speakers say
in real life. The average speaker is not a grammarian.

If you said 「乗るから」 instead of 「乗るんだから」, then it would probably satisfy
everyone. But who speaks his native language to satisfy everyone?

Interestingly, though, it would sound 100% natural (instead of just 90% as it
does now) if you switched the two clauses and uttered them as two sentences as
in:

> 「早く支度しなさい！10時半のバスに乗るんだから！」

That would just wipe out the small amount of awkwardness of the original
sentence above.

Moving on...

> Which of the following are grammatically sound?
>
> んですから / んだから
>
> んですので / んだので
>
> んものですから / んものだから

んですから and んだから are unquestionably sound.

んだので is sound in 飲{の}んだので, 死{し}んだので, etc. but you _**cannot**_ say 「乗るんだので」.

んものですから and んものだから are simply out of the question.




> 「10時半{じはん}のバスに乗{の}るんだから、早{はや}く支度{したく}しなさい。」

This sentence would sound O.K. and even fairly natural, if not perfect, **if
it were uttered by a busy mom in an informal situation**. Grammarians might
disagree here, but it is something you would actually hear native speakers say
in real life. The average speaker is not a grammarian.

If you said 「乗るから」 instead of 「乗るんだから」, then it would probably satisfy
everyone. But who speaks his native language to satisfy everyone?

Interestingly, though, it would sound 100% natural (instead of just 90% as it
does now) if you switched the two clauses and uttered them as two sentences as
in:

> 「早く支度しなさい！10時半のバスに乗るんだから！」

That would just wipe out the small amount of awkwardness of the original
sentence above.

Moving on...

> Which of the following are grammatically sound?
>
> んですから / んだから
>
> んですので / んだので
>
> んものですから / んものだから

んですから and んだから are unquestionably sound.

んだので is sound in 飲{の}んだので, 死{し}んだので, etc. but you _**cannot**_ say 「乗るんだので」.

んものですから and んものだから are simply out of the question.

