-는지 모르겠다 expresses uncertainty or lack of knowledge about something. It means "I'm not sure," "I don't know if/whether," or "I can't tell if."
Structure
Verb/Adjective + -는지 모르겠다
Complete pattern: Question word/clause + -(으)ㄴ/는지 + 모르겠다
Meaning: "I don't know if/whether..."
Basic Forms
With Action Verbs: -는지
Present tense uncertainty:
- 가는지 모르겠어요 (I don't know if they're going)
- 오는지 모르겠어요 (I don't know if they're coming)
- 하는지 모르겠어요 (I don't know if they're doing it)
- 있는지 모르겠어요 (I don't know if it exists)
With Adjectives: -(으)ㄴ지
State uncertainty:
- 좋은지 모르겠어요 (I'm not sure if it's good)
- 맞는지 모르겠어요 (I'm not sure if it's correct)
- 큰지 모르겠어요 (I don't know if it's big)
- 어려운지 모르겠어요 (I'm not sure if it's difficult)
With Past Tense: -았/었는지
Past uncertainty:
- 갔는지 모르겠어요 (I don't know if they went)
- 했는지 모르겠어요 (I don't know if they did it)
- 먹었는지 모르겠어요 (I don't know if they ate)
- 왔는지 모르겠어요 (I don't know if they came)
Question Word Patterns
뭐 (What) + -ㄴ지/는지
What uncertainty:
- 뭔지 모르겠어요 (I don't know what it is)
- 뭐 하는지 모르겠어요 (I don't know what they're doing)
- 뭘 먹었는지 모르겠어요 (I don't know what I ate)
어디 (Where) + -ㄴ지/는지
Where uncertainty:
- 어딘지 모르겠어요 (I don't know where it is)
- 어디 가는지 모르겠어요 (I don't know where they're going)
- 어디 있는지 모르겠어요 (I don't know where it is)
언제 (When) + -ㄴ지/는지
When uncertainty:
- 언젠지 모르겠어요 (I don't know when it is)
- 언제 오는지 모르겠어요 (I don't know when they're coming)
- 언제 시작하는지 모르겠어요 (I don't know when it starts)
왜 (Why) + -ㄴ지/는지
Why uncertainty:
- 왜 그런지 모르겠어요 (I don't know why)
- 왜 안 오는지 모르겠어요 (I don't know why they're not coming)
- 왜 안 되는지 모르겠어요 (I don't know why it doesn't work)
누구 (Who) + -ㄴ지/는지
Who uncertainty:
- 누군지 모르겠어요 (I don't know who it is)
- 누가 했는지 모르겠어요 (I don't know who did it)
어떻게 (How) + -ㄴ지/는지
How uncertainty:
- 어떻게 하는지 모르겠어요 (I don't know how to do it)
- 어떻게 가는지 모르겠어요 (I don't know how to get there)
Politeness Levels
Casual: -는지 모르겠어
Informal:
- 가는지 모르겠어 (I don't know if they're going)
- 뭔지 모르겠어 (I don't know what it is)
Polite: -는지 모르겠어요
Standard polite:
- 가는지 모르겠어요 (I don't know if they're going)
- 뭔지 모르겠어요 (I don't know what it is)
Formal: -는지 모르겠습니다
Very formal:
- 가는지 모르겠습니다 (I don't know if they're going)
- 뭔지 모르겠습니다 (I don't know what it is)
Expressing Personal Uncertainty
About One's Own State
Self-reflection:
- 뭘 해야 할지 모르겠어요 (I don't know what I should do)
- 어떻게 해야 할지 모르겠어요 (I don't know how I should do it)
- 맞는지 모르겠어요 (I'm not sure if I'm right)
About Feelings
Uncertain emotions:
- 좋은지 나쁜지 모르겠어요 (I don't know if it's good or bad)
- 행복한지 모르겠어요 (I don't know if I'm happy)
Common Variations
-는지 잘 모르겠다
Adding 잘 (well) for emphasis:
- 뭔지 잘 모르겠어요 (I really don't know what it is)
- 어떻게 하는지 잘 모르겠어요 (I really don't know how to do it)
Nuance: Emphasizes the degree of uncertainty
-는지 모르겠네(요)
Adding -네 for realization:
- 뭔지 모르겠네요 (I realize I don't know what it is)
- 왜 그런지 모르겠네요 (I realize I don't know why)
Softening Statements
Humble Expression
Showing modesty:
- 맞는지 모르겠어요 (I'm not sure if it's correct - being humble)
- 좋은지 모르겠어요 (I'm not sure if it's good - uncertain)
Usage: Polite way to give opinions
Expressing Confusion
Inability to Understand
Genuine confusion:
- 무슨 말인지 모르겠어요 (I don't understand what you're saying)
- 왜 그런지 모르겠어요 (I don't understand why)
- 무슨 뜻인지 모르겠어요 (I don't know what it means)
Comparison with Similar Patterns
-는지 모르겠다 vs 모르다
모르다 (don't know - simple):
- 몰라요 (I don't know)
- Direct, simple
- About facts
-는지 모르겠다 (don't know if/whether):
- 뭔지 모르겠어요 (I don't know what it is)
- About circumstances
- More complex uncertainty
-는지 모르겠다 vs -ㄹ지 모르다
-ㄹ지 모르다 (might/may):
- 올지 몰라요 (They might come)
- Possibility
- About future
-는지 모르겠다 (don't know if):
- 오는지 모르겠어요 (I don't know if they're coming)
- Current uncertainty
- About present situation
-는지 모르겠다 vs -는지 알다
-는지 알다 (know if/whether):
- 뭔지 알아요 (I know what it is)
- Positive knowledge
-는지 모르겠다 (don't know if):
- 뭔지 모르겠어요 (I don't know what it is)
- Lack of knowledge
Usage Contexts
Asking for Information
Admitting lack of knowledge:
- 어디 있는지 모르겠어요. 아세요? (I don't know where it is. Do you know?)
- 언제인지 모르겠어요 (I don't know when it is)
Expressing Doubt
Uncertain about something:
- 맞는지 모르겠어요 (I'm not sure if it's right)
- 될지 모르겠어요 (I'm not sure if it'll work)
Showing Modesty
Humble opinions:
- 좋은 방법인지 모르겠어요 (I'm not sure if it's a good method)
- 맞는 답인지 모르겠어요 (I'm not sure if it's the right answer)
With Negative Forms
Uncertainty About Negatives
Not sure if something ISN'T:
- 안 오는지 모르겠어요 (I don't know if they're not coming)
- 없는지 모르겠어요 (I don't know if there isn't)
- 안 좋은지 모르겠어요 (I'm not sure if it's not good)
Temporal Aspects
Present Uncertainty
About current situation:
- 지금 뭐 하는지 모르겠어요 (I don't know what they're doing now)
- 어디 있는지 모르겠어요 (I don't know where they are)
Past Uncertainty
About past events:
- 언제 갔는지 모르겠어요 (I don't know when they went)
- 뭘 먹었는지 모르겠어요 (I don't know what I ate)
Future Uncertainty
About future plans:
- 언제 올지 모르겠어요 (I don't know when they'll come)
- 뭘 할지 모르겠어요 (I don't know what I'll do)
Common Expressions
잘 모르겠어요
I don't really know:
- Most common way to express uncertainty
- Polite and humble
뭐라고 해야 할지 모르겠어요
I don't know what to say:
- When at a loss for words
- Speechless situation
어떻게 해야 할지 모르겠어요
I don't know what to do:
- When confused about action
- Seeking guidance
확실하지 않아서 잘 모르겠어요
I'm not certain so I don't really know:
- Emphasizing uncertainty
- Being careful
Idiomatic Uses
뭔지는 모르겠지만
I don't know what it is, but...:
- 뭔지는 모르겠지만 좋아요 (I don't know what it is, but I like it)
- Acknowledging uncertainty while continuing
왜인지는 모르겠지만
I don't know why, but...:
- 왜인지는 모르겠지만 기분이 좋아요 (I don't know why, but I feel good)
Embedded in Longer Sentences
As Reason Clause
Using uncertainty as explanation:
- 뭔지 모르겠어서 사지 않았어요 (I didn't buy it because I don't know what it is)
- 어떻게 하는지 모르겠어서 못 했어요 (Couldn't do it because I don't know how)
Summary Table
| Question Word | Pattern | Example | Meaning |
|---|---|---|---|
| 뭐 (what) | 뭔지 모르겠다 | 뭔지 모르겠어요 | I don't know what it is |
| 어디 (where) | 어딘지 모르겠다 | 어딨는지 모르겠어요 | I don't know where it is |
| 언제 (when) | 언젠지 모르겠다 | 언제인지 모르겠어요 | I don't know when it is |
| 왜 (why) | 왜...는지 모르겠다 | 왜 그런지 모르겠어요 | I don't know why |
| 누구 (who) | 누군지 모르겠다 | 누군지 모르겠어요 | I don't know who it is |
| 어떻게 (how) | 어떻게...는지 모르겠다 | 어떻게 하는지 모르겠어요 | I don't know how |
Key Points
Use -는지 모르겠다 for:
- Expressing uncertainty
- Admitting lack of knowledge
- Showing modesty
- Asking indirect questions
- Softening statements
Remember:
- Very common in daily conversation
- Polite way to express uncertainty
- Can be used with all question words
- Different from -ㄹ지 모르다 (possibility)
- Essential for natural Korean