i want to settle this once and for all since i cant find any legitimate source about this grammar pattern and i see very different answers online. some say they are interchangable, some say the nuance is in fact different. when used in a question clause, how do i know which one to choose?

it's just my feeling but the closest literal way i would translate these sentences would be something like this:

i want to know what you did.

I want to know what(is it that) you did.
#this has a slight more interrogative feel.

is that correct? or am i missing something..?

1 Answer 1


This is just my feeling as a native Japanese speaker. They are interchangeable in most cases but have different implicit nuances.

Some articles just say "interchangeable" because the differences are really tiny, especially verbal communication. For beginners or intermediate-level learners, it doesn't matter, because the nuances are less than the pronunciation effect, so until your pronunciation becomes perfect as native, they are interchangeable.

On the other hand, when it is used in text like a novel, lyrics, dialogue, etc... the author has the reason why choose one.

And your feeling is correct. "のか" has some more pressure than just "か".

But this is not always correct. In this sentence "君が何したのかしりたい", it is used "君" and "が" and "何した". They are also some alternative like "あなた", "お前" or "(name)", and "は", and "何をした".

For example, those sentences are also translated "I want to know what you did"

  • 君  が何をしたのかしりたい
  • お前 が何をした かしりたい
  • あなたは何をしたのかしりたい
  • etc...

but the nuances or images are different.

So those words already show some relationship between "you" and "I" and some situation.

  • "君" means "I" are higher position than "you" or really closer with "you".
  • "何したか" have impatience feeling than "何をしたか".
  • "が" feels like not one of them but you(Obj) than "は".

In brief, the sentence feels like "I" doubt something about "you" already. So in this situation, "のか" make the sentence some more interrogative because the "のか" emphasize the feeling.

In my opinion, "のか" can emphasize the sentence's feelings than just "か". So If the sentence just has flat nuance, they are interchangeable. For example, (I want to know who did fix the problem.)

  • 誰がその問題を解決したのかしりたい
  • 誰がその問題を解決した かしりたい

They are the same feeling, But if

  • 君がその問題を解決したのかしりたい (I doubt you but...)
  • 君がその問題を解決した かしりたい (I just want to know if you did)

They are not the same for me.

I hope it helps you!

  • 1
    that was a perfect answer! very good breakdown. thank you so much, i could kind of understand it but not fully because of the contrasting advices and lack of a concrete explanation so i was feeling very unsure. you helped me alot !
    – Dani1911
    Jul 4, 2021 at 13:25

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