くださるんじゃ...: Formal, semi-casual, poor usage, etc.?


> それって先生が決めて、一緒に行ってくださるんじゃ…。

*From [Japanesetest4you](http://japanesetest4you.com/japanese-language-proficiency-test-jlpt-n3-listening-exercise-6/ "JT4Y").

**My understanding:**

  1. **くださる** is the honorific version of **くれる**

  2. **ん** is from **の** , **explanatory**

  3. **じゃ** , contracted **では** , usually in the form of **rhetorical じゃない** , or the slangy **じゃん**

**My problem here:**

  1. Is **ない** left out of the sentence? I think I've only seen **じゃない/じゃん** so far.

  2. **くださる** is **尊敬語** unless I had been hopelessly mistaken for months. However, this **くださるんじゃ** somehow looks, and sounds really casual to me. Is the speaker sneaking in a hint of **砕けた言い方** in the guise of **敬語**? I also feel that by speaking this way, the speaker is hiding a sense of affected ignorance of responsibility, but I may be reading too much into this. 

教えていただけませんか。お願いいたします！




  1. 「ないんですか？」 or something similar is left out after 「～んじゃ...」

The full sentence would be like:

> それって先生が決めて、一緒に行ってくださるんじゃ **ないんですか？**

but it's quite common to cut off sentences like this in daily conversation.
And I think you'd usually sound a bit less decisive/interrogatory and
therefore a bit more humble and softer when speaking this way.

Example:

「これって、間違ってるんじゃ **ないですか** ？」→「これって、間違ってるんじゃ・・・」

* * *

  2. You're right that 「くださるんじゃ…」 is a bit more casual than 「くださるのでは…」. 「くださるのでは（ないのですか？ / ありませんか？）」 would sound more formal. 




  1. 「ないんですか？」 or something similar is left out after 「～んじゃ...」

The full sentence would be like:

> それって先生が決めて、一緒に行ってくださるんじゃ **ないんですか？**

but it's quite common to cut off sentences like this in daily conversation.
And I think you'd usually sound a bit less decisive/interrogatory and
therefore a bit more humble and softer when speaking this way.

Example:

「これって、間違ってるんじゃ **ないですか** ？」→「これって、間違ってるんじゃ・・・」

* * *

  2. You're right that 「くださるんじゃ…」 is a bit more casual than 「くださるのでは…」. 「くださるのでは（ないのですか？ / ありませんか？）」 would sound more formal. 

