Hi.
I give you some examples. '누구' and '누구랑'.
You can use '누구'.
Who is this?
Who are you?
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You can use this '누구랑 or 누구와'. > It means 'with you / with me / with+Name'.
(O) I go to movie with my friend tonight. (나는 친구랑 / 친구와 영화를 보러 갑니다.)
(X) I go to movie with tonight. (나는 밤과 영화를 보러 간다.)