you use co? (and czego, czemu, czym) when the answer is noun,
you use jaki? when answer is a description of a noun.
So how do you say "what are you doing?" Doesn't that use "co"? The answer isn't a noun in that case
I guess that was too simplified. "what" is like an 'adjectival what', it's more descriptive, it can often (but not always) be translated as "what kind/type/sort of". It's hard to explain that difference precisely...
Why is wrong "what kind of question is yours?" Meaning your question is inappropiate or out of place? Thanks
That's not how you say it in English. "What kind of question is that?" in Polish: "Co to za pytanie?"
Why in this sentence with 'jest' not one of the two words 'compared' is instrumental ?
From the grammar I have seen so far I would conclude:
Jakie (Nom. Sg Neut) To twoje pytanie (Nom Sg Neut)
or with 'jest' one of the following options:
1- Jakie (Nom sg n) jest twoim pytaniem. (instr. sg n)
2- Jakim (instr sg n) jest twoje pytanie.
This apparently is not happening. Why ?
Imagine that the answer to this question is "strange". "Twoje pytanie jest dziwne" = "Your question is strange". And you can see, that such a sentence will simply take Nominative for 'strange', as it is not a noun phrase but just an adjective.
And thus, the question itself also takes Nominative for "jakie".
So the answer to "What is your question?" is not some question, but a description of the question?
OK, that didn't take everything into consideration. Of course the most common answer to "Jakie jest twoje pytanie?" is actually stating your question, not describing the question as 'strange'. However, that doesn't change the fact that you still use "Jakie".