This is the 7832nd most frequent Korean word.
했나
"했나" translates to "did (it)?" in English, often used to ask if an action was done.
In this sentence, '했나' is used in conjunction with '그 일' (that task) to pose a question about whether it was done.
그 일을 정말 했나 확인해보자.
Let's check if they really did that.
Here, '했나' refers to the act of completing the homework ('숙제') and is used to express uncertainty in the past tense.
어제 숙제를 했나 못했나 기억이 안 나요.
I can't remember if I did the homework or not yesterday.
In this sentence, '했나' is part of an assumption ('했나 봐요') indicating that studying ('시험 공부') might have taken place.