If 언제 means when and 언제나 means always, what does -나 mean in this case? I know that a combination of words does not always literally mean the separate meanings glued together yet usually they are related. For example "whenever" could literally be defined as "at any point in time that this condition is met" which is the meanings of "when" and "ever" combined. So, what definition of -나 fits here because the closest I can find is "wondering to oneself" but that doesn't come close.

What does 시 in 왜 예쁜 날 두고 가시나 mean? From what I know of korean so far, the sentence 왜 예쁜 날 두고 가시나 means "Why are you leaving pretty me behind?" 왜 (why) 예쁜 날 (pretty me as the object) 두고 가 (place and go -> to leave behind) -시 (??) -나 (makes it a question) I can't find any definition that fits with -시, though. If I didn't get the other parts right, please tell me too.