-무엇(what) The interrogative pronoun 무엇 means "what". In speech, it is often contracted to 뭐: 이게 뭐예요? What is this? 뭐라고 했어요? What did you say? 뭐하니? What are you doing? -누구(who) When a subject particle 가 is attached, a form 누가 ‎(nuga) should be used instead of 누구가. 누가 집에 있어요? Who is at home? 누구를 만났어요? Whom did you meet? -언제(when) 언제가 네 생일이니?‎ When is your birthday? 언제 집에 갔어요? When did you go home? -어떻게(how) 내가 그 시험에 어떻게 통과하지?‎ How can I pass the exam? 어떻게 집에 갔어요? How did you go home? -어디(where) 공항까지 지하철을 타면 될 것 같은데 혹시 지하철이 어디 있는지 아세요?‎ I think I can take the subway to the airport. Do you know where the subway is? 어디 가세요? Where do you go? -왜(why) 너는 이 가수를 왜 좋아하지?‎ Why do you like this singer? 왜 집에 갔어요? Why did you go home?