I learned in Tae Kim's Grammar Guide that だ cannot be used when asking a question. But in the book Japanese Sentence Patterns for Effective Communication by Taeko Kamiya, I found several example sentences that used だ in a question. I also have seen it being used this way in anime.

I'm guessing there is some type of exception to all of this? Anyways, I hope someone can shed some light on the subject for me. :)

== EDIT ==

Here is an example from the aforementioned book:

どうしてゆうべ来なかったんだ? (Why didn't you come last night?)

And here is an example from the title of the 249th episode of the show Dragon Ball Z:

悟飯はどこだ!? (Where's Gohan!?)

  • Can you provide such examples ? Tae Kim seems right to me. Note that it could possibly be used in oral speech, people would understand it but it wouldn't be 100% correct (like saying ありがとうございました).
    – Aki
    Sep 8, 2011 at 4:57
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    @aki: indeed, OT for this question, but since you mention it: What in the world makes you think 'ありがとうございました' is incorrect??
    – Dave
    Sep 8, 2011 at 6:47
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    I argued this in the Tae Kim forums long ago. Yet here it is, still in the guide after all this time. In fact, I've never heard of him editing that thing.
    – Claytonian
    Sep 8, 2011 at 10:55
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    You ought to ask for a refund!
    – Matt
    Sep 8, 2011 at 12:16
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    Don't get me wrong, his approach to Japanese was super helpful, and he says things that no other textbook will acknowledge though they be right. Another odd memory is that he was provided with info on why "同じ" appears to break some rules, but his question to the world on that is still in the guide AFAIK.
    – Claytonian
    Sep 8, 2011 at 22:17

2 Answers 2


Yes, it can be used in a question, as long as the sentence also contains a question word: だれ, なに, どこ, etc.

  • 誰だ? = Who's there?
  • 何やってんだよ = What (the hell) are you doing? - (Note that よ can be added at the end)

Both of your examples fit this pattern: どうして and どこ are the question words.

Without a question word, you are much less likely to see this pattern, although there are a few special/edge cases that might technically count as use of だ. For example: "友達だぁ?・・・ふざけるな!" = "'Friends'?! Don't give me that crap!"

Update: As Axioplase says in comments, this is a very informal non-polite way of asking a question (it is だ, not です, after all), and can also carry a "confrontational" or "accusatory" nuance -- especially when combined with ん, when it becomes less a question ("what are you doing?") and more of a demand for an explanation ("why are you doing that?").

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    However obvious it may seem, I think that you need to say that it's fairly oral and familiar…
    – Axioplase
    Sep 8, 2011 at 8:11
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    You are right that using だ as in 誰だ or 何をしているのだ can often be confrontational or accusatory, but I do not find it informal. Sep 8, 2011 at 16:00
  • Hm, okay - how's the new version?
    – Matt
    Sep 8, 2011 at 20:43
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    And what if the question was: "Can だ ever be used with か(question mark) ? In format speech or writing I think Tae Kim's rule may be right, what do you think ?
    – Aki
    Sep 14, 2011 at 10:55
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    Yeah, that'd be ungrammatical, I think. There are utterances like どうだか ("I wonder!" -- expressing doubt) but I suppose they are better viewed as fragments of an implied larger whole (e.g. どうだか知らないけど) where か is functioning slightly differently.
    – Matt
    Sep 14, 2011 at 11:28

It may be worth noting that the だ form is the most informal. You might ask a question this way (なんだろう!) but only to someone of a lower rank..


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