「なん」as a formal, spoken, suffix for questions?


I sense that using "なん" in questions probably makes the question sound more
formal:  
"どこですか？"  
"どこなんですか？" // maybe more formal?  
"いつですか？"  
"いつなんですか？" // maybe more formal?  
"だれですか?"  
"だれなんですか？" // maybe more formal?  
....

Am I right about this? Maybe this is very similar to the function of
[美化語]{びかご}?

But, I don't remember ever seeing this in written Japanese. I suspect that
this is just because using fewer characters trumps whatever formality "なん"
may, or may not, inject into questions?




I don't think なん is particularly formal. It's short for なの. If I understand
the traditional grammar right, な here is analyzed as 断定の助動詞「だ」の連体形「な」, a form
which appears chiefly before the 形式名詞「の」 in constructions such as
「〜なのだ」「〜なので」「〜なのに」「〜なのか」 and so on.

I think it's like this:

[code]

    　どこ **だ**　＋　のだ　＝　どこ **な** のだ
    
[/code]

So the difference in meaning is the same you get from adding 〜のだ to a
sentence.

* * *

If you take the above and change だ to です and add か, then you've almost got
your original example. You just need to change の to ん:

[code]

    　どこな **の** ですか　→　どこな **ん** ですか
    
[/code]

I think that this の can change to ん before forms of the copula and before the
question particle か, but like most reduced forms it's less formal than the
full version. It can even be reduced to ん at the end of a sentence in certain
dialects, but you should be aware that this is not considered standard
Japanese.




I don't think なん is particularly formal. It's short for なの. If I understand
the traditional grammar right, な here is analyzed as 断定の助動詞「だ」の連体形「な」, a form
which appears chiefly before the 形式名詞「の」 in constructions such as
「〜なのだ」「〜なので」「〜なのに」「〜なのか」 and so on.

I think it's like this:

[code]

    　どこ **だ**　＋　のだ　＝　どこ **な** のだ
    
[/code]

So the difference in meaning is the same you get from adding 〜のだ to a
sentence.

* * *

If you take the above and change だ to です and add か, then you've almost got
your original example. You just need to change の to ん:

[code]

    　どこな **の** ですか　→　どこな **ん** ですか
    
[/code]

I think that this の can change to ん before forms of the copula and before the
question particle か, but like most reduced forms it's less formal than the
full version. It can even be reduced to ん at the end of a sentence in certain
dialects, but you should be aware that this is not considered standard
Japanese.

