Quote Originally Posted by Оля
Quote Originally Posted by sperk
Как "не могу знать" отличается от "не знаю"?
Спасибо
That is an outdated variant usually used by a subordinate addressing a superior and it means something like "I am sorry, but I don't know, I can't know that, I am only a cog, an underling, so don't ask me and please don't make me responsible".

Briefly, "I don't know, and knowing that is not my duty". The phrase, anyway, means sycophancy.

P.S. Your question sounds okay, but "чем отличается..." would make your sentence perfect.
Спасибо