Core Pattern Rule: Guessing with -(으)ㄴ/나 봐
This pattern is used to express a guess or assumption based on something you've observed or experienced. It's a softer, more indirect way of stating something you believe to be true but aren't 100% certain about. The English equivalent is often "I guess...", "It seems like...", or "It looks like...".
Formation Rules
The ending changes based on the type of word it attaches to.
1. Action Verbs (e.g., 가다, 먹다):
Present Tense: Verb stem + -나 봐(요)
e.g., 자다 → 자나 봐요 (I guess he's sleeping.)
Past Tense: Verb stem + -았/었나 봐(요)
e.g., 고장 나다 → 고장 났나 봐요 (I guess it broke.)
Future Tense: Verb stem + -(으)려나 봐(요)
e.g., 오다 → 오려나 봐요 (I guess it's going to rain.)
2. Descriptive Verbs / Adjectives (e.g., 예쁘다, 춥다):
Vowel Stem: Verb stem + -ㄴ가 봐(요)
e.g., 바쁘다 → 바쁜가 봐요 (I guess she's busy.)
Consonant Stem: Verb stem + -은가 봐(요)
e.g., 작다 → 작은가 봐요 (I guess it's small.)
3. Nouns:
Noun + -인가 봐(요)
e.g., 학생 → 학생인가 봐요 (I guess he's a student.)
4. 있다 / 없다:
These follow the action verb rule: 있나 봐(요) / 없나 봐(요)
e.g., 재미있다 → 재미있나 봐요 (I guess it's fun.)
비가 오려나 봐. / 걔가 널 좋아하나 봐. / 배가 고픈가 봐. / 고장 났나 봐. / 재미있나 봐.
Verbs vs. Adjectives: -나 봐 vs. -(으)ㄴ가 봐
The most important distinction to master for this pattern is choosing the correct ending for action verbs versus descriptive verbs (adjectives). Mixing these up is a common mistake for learners.
Action Verbs & 있다/없다 → -나 봐(요)
Use -나 봐(요) when you are guessing about an action or a state of existence.
Action: 자나 봐 (I guess he's sleeping), 좋아하나 봐 (I guess he likes her).
Past Action: 취했나 봐 (I guess I'm drunk), 사랑에 빠졌나 봐 (I guess I fell in love).