Thread: 'Have you eaten?' and 'Did you eat?'

Originally Posted by car

Note that aspects have slightly different meanings in interrogative sentences, as opposed to declarative sentences.

And in negative sentences as well.
Compare:
- Это ты разбил окно? - Is it you who broke the window?
- Нет, я не разбивал его. - No, I did not break it.

The questions uses a perfective verb here, because the window is broken (so, we get the result).
The negative answer uses an imperfective verb, because there was no action at all, it did not even start. If the answerer replied as "Я не разбил окно" (with the perfective verb), it would sound as if he tried to break it, but failed to get a result.