I recently started to learn japanese, and I'm having trouble to distinguish some of it's phrase structures. I learned that だ is often used in informal situations representing the です form and か is used to represent a question.

What I really like to know is if the なんだこれ can be used as an answer for これわなんだか. For example:

これわなんだか - What is this?
I don`t know, なんだこれわ.

I'm sorry if it sounds a noobie question, but I get a hard time figuring out how it's structures, because there isn't always a pattern, for instance, I know about SOV fundamentals, I just don't get the other possible combinations.

  • Where did you learn to say 「これわなんだか。」 to mean "What is this?" It is 「は」 and not 「わ」, but that is not even the point. Whether it is a book or website that you are using, you would need to start looking for a better one very soon - like right now.
    – user4032
    Aug 19, 2017 at 16:12
  • @l'électeur I didn't learn it anywhere I just assumed based on what I've learned so far, which were, これ meaning something like "this", なに meaning "what" and I thought だ was the impolite form for です. Aug 19, 2017 at 16:16

1 Answer 1


First, わ is written as は in your context because the は(wa) is the subject/topic indicating particle.

これはなんだか cannot mean "what is this?"

"What is this?" should be これはなんですか。or これはなんだろうか。

これはなにか。is also grammatically correct, meaning "what is this?" But it's too impolite, offensive and demanding. So we usually don't use it in our daily life.

これはなんだか means something completely different: "Oops! This seems rather..."

なんだこれ=なんだこれは=これはなんだ="What is this?" In some contexts, it means, "I don't know what this is."

  • I see so for now on I'll be using the は mora as the subject/topic particle. I've noticed that you used ですか instead of だか, but isn't だ the less polite form of です? And why did you put the ろう between これはなんだ and か? Aug 19, 2017 at 16:00
  • The combination of です+か is possible. However unfortunately, the combination of だ+か is not available. なんだろう can be available, and なんだろう+か is a possible combination.
    – user1118
    Aug 19, 2017 at 16:16
  • これはなんだろうか=I wonder what this is.
    – user1118
    Aug 19, 2017 at 16:18

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