So that is how you can understand why the "did" is there. It's an auxiliary which is inserted to replace a null auxiliary once subject-aux inversion takes place (do affixing), and at the …
"Why you did that" is wrong merely because of the sentence structure. The other guy is right to correct it to "why did you do that". You must state the tenses clearly and somewhat early. …
With "Why did you do that?", you're asking about the decisions and circumstances around that past event. Let's say you broke an ornament (which you hate) by accident, and your partner …
Why didn't somebody do something? The other way is not wrong. Why did somebody not do something? Putting the not outside of the normal order causes more emphasis to be placed …
Ironically, although this form is archaic, it is virtually supplanted by exactly the same thing. We routinely use “have you …” or “did you …” to ask the same question. “Went you … ?” has …
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