Want to say “I know if…” or “I don’t know whether…” in Korean? The grammar pattern ‘(으)ㄴ/는지 알다/모르다’ is essential for expressing whether you know a fact, answer a question, or recognize a situation. In this post, you’ll learn how to use it naturally with clear explanations, real-life examples, and practice exercises.
Contents
1. Definition
‘(으)ㄴ/는지 알다/모르다’ is used to express whether the speaker knows or doesn’t know something. It corresponds to the English expressions:
- “know if/whether…”
- “don’t know if/whether…”
2. Form (Structure)
The grammar pattern ‘-ㄴ/은/는지 알다/모르다’ changes its ending depending on the type of word it attaches to: verbs, adjectives, or nouns. The following rules apply:
| Word Type | Rule | Example |
| Verb (present) | Verb stem + 는지 알다/모르다 | 가는지 알다 (to know if going) |
| Verb (past) | Verb stem + 았/었는지 알다/모르다 | 갔는지 알다 (to know if went) |
| Adjective | Adjective stem + (으)ㄴ지 알다/모르다 | 좋은지 알다 (to know if good) 빠른지 알다 (to know if fast) |
| Noun + 이다 (present) | Noun + 인지 알다/모르다 | 학생인지 알다 (to know if student) |
| Noun + 이다 (past) | Noun + 였는지/이었는지 알다/모르다 | 학생이었는지 알다 (to know if was student) |
For adjectives, the ending is chosen based on whether the adjective stem ends with a consonant (받침) or not:
- If the adjective stem has no final consonant (받침이 없을 때), use -ㄴ지.
- If the adjective stem has a final consonant (받침이 있을 때), use -은지.
For nouns with ‘이다’ in the past tense, use -이었는지 after nouns ending with a consonant, and -였는지 after nouns ending with a vowel.
3. Meaning & Usage
1. To say you know or don’t know a fact
- 민지가 어디에 사는지 몰라요.
(I don’t know where Minji lives.) - 지금 가게가 열었는지 잘 모르겠어요.
(I’m not sure if the store is open now.) - 이거 얼마인지 알아요?
(Do you know how much this is?) - 수업이 언제 끝나는지 모르겠어요.
(I don’t know when the class ends.) - 이 약이 효과가 있는지 알아요?
(Do you know if this medicine works?)
2. To express uncertainty or curiosity about something
- 그 사람이 한국 사람인지 모르겠어요.
(I’m not sure if that person is Korean.) - 친구가 이걸 좋아할지 모르겠어요.
(I don’t know if my friend will like this.) - 지금 가도 늦었는지 모르겠어요.
(I don’t know if it’s already too late.) - 어제 그가 학교에 왔는지 아세요?
(Do you know if he came to school yesterday?) - 날씨가 내일 어떤지 몰라요.
(I don’t know what the weather will be like tomorrow.)
3. Often used with question words
(누구 who, 어디 where, 언제 when, 왜 why, 어떻게 how, 얼마나 how much/how many)
- 이 음식이 왜 인기 있는지 모르겠어요.
(I don’t know why this food is popular.) - 요즘 그 친구가 어떻게 지내는지 아세요?
(Do you know how that friend is doing these days?) - 저 배우가 얼마나 유명한지 알아요?
(Do you know how famous that actor is?) - 시험이 어려운지 쉬운지 모르겠어요.
(I don’t know if the test is hard or easy.) - 우리가 어디서 만나는지 기억이 안 나요.
(I don’t remember where we’re supposed to meet.)
4. Can be used to express reported questions
- 민지가 언제 오는지 물어봤어요.
(I asked when Minji is coming.) - 선생님이 우리가 숙제를 했는지 알고 계세요.
(The teacher knows if we did the homework.) - 그가 누구인지 궁금해요.
(I’m curious who he is.) - 부모님이 제가 어디에 있는지 모르세요.
(My parents don’t know where I am.) - 이게 맞는지 확실하지 않아요.
(I’m not sure if this is correct.)
4. Key Points to Remember
- Use -는지 for present tense verbs.
- Use -았/었는지 for past tense verbs.
- Use -(으)ㄴ지 for adjectives.
- Use -인지 for nouns with 이다.
- Often used with verbs like 알다, 모르다, 궁금하다, 기억하다, and adjectives like 확실하다.
- Commonly combined with question words: 누구 (who), 어디 (where), 언제 (when), 왜 (why), 어떻게 (how), 얼마나 (how much/how many).
5. Practice Exercises
Fill in the blanks with the correct form of ‘(으)ㄴ/는지 알다/모르다’.
- 민지가 어디 __________ 몰라요. (I don’t know where Minji is.)
- 그 가수가 유명한지 __________? (Do you know if that singer is famous?)
- 시험이 언제 시작하는지 __________? (Do you know when the test starts?)
- 어제 비가 왔는지 __________요? (Do you know if it rained yesterday?)
- 저 사람 이름이 뭐 __________ 몰라요. (I don’t know what that person’s name is.)
- 요즘 민수가 잘 지내는지 __________? (Do you know if Minsu is doing well these days?)
- 이 음식이 얼마나 매운지 __________요? (Do you know how spicy this food is?)
- 그 사람이 학생인지 아닌지 __________요? (Do you know if that person is a student or not?)
- 민수가 왜 화났는지 __________. (I don’t know why Minsu is angry.)
- 오늘 회의가 몇 시에 시작하는지 __________요? (Do you know what time the meeting starts today?)
6. Answers
- 사는지
- 알아요
- 알아요
- 아세요
- 인지
- 아세요
- 아세요
- 아세요
- 모르겠어요
- 아세요
7. Common Mistakes and Tips
⚠️ Mistake 1: Using ‘-는지’ for adjectives
Incorrect: 이 음식이 맛있는지 알아요? ❌ (Do you know if this food is delicious?)
Correct: 이 음식이 맛있는지 알아요. ✅ (Do you know if this food is delicious?)
💡 Tip: For adjectives, use ‘-(으)ㄴ지’ (for example, 맛있는지, 예쁜지, 빠른지) even in the present tense.
⚠️ Mistake 2: Using ‘(으)ㄴ지’ for present tense verbs
Incorrect: 지금 친구가 도착한지 알아요? ❌ (Do you know if your friend arrives now?)
Correct: 지금 친구가 도착하는지 알아요? ✅ (Do you know if your friend is arriving now?)
💡 Tip: For present actions or ongoing situations, use ‘-는지’.
⚠️ Mistake 3: Forgetting to conjugate 알다/모르다 properly
Incorrect: 어디 사는지 알. ❌ (Know where someone lives.)
Correct: 어디 사는지 알아요. ✅ (Do you know where someone lives?)
💡 Tip: Don’t forget to conjugate ‘알다’ or ‘모르다’ based on tense and politeness.
The Korean grammar pattern ‘(으)ㄴ/는지 알다/모르다’ is a key structure that helps learners express whether they know or don’t know a piece of information. It’s widely used in questions, indirect speech, and expressions of uncertainty. By mastering this pattern, students can ask and answer questions more naturally and clearly in Korean.