"Proč ses ptala, jak dlouho už tam bydlí?"

Translation: Why did you ask how long they had been living there?

[teabeadle]

The "už" does not show up in the English translation. At least "... had been living there already" should also be accepted.

[VladaFu]

It is accepted and has been for at least two years.

[ken55414]

I thought that I was making progress on understanding perfective/imperfective, but why is “Proč ses ptala ...” translated as “Why did you ask ...” instead of “Why were you asking ,,, .” Shouldn't “Why did you ask ...” be translated as “Proč ses zeptala ...” ?

[VladaFu]

Both are accepted. I think you raised a valid point, but in this specific case semantic difference between those two grammatical options is very small.