🔎

Based on Evidence: -나 보다 / -(으)ㄴ가 보다

Keywords
-나 보다
Lesson #
S
Done
Section
Intermediate Grammar
🎯
TL;DR 🦄
  • 🔍 -나 보다 [-na bo-da] and -(으)ㄴ가 보다 [-(eu)n-ga bo-da] mean it seems / I guess / apparently based on evidence.
  • Use it when you are inferring from clues, not just randomly guessing.
  • It is usually softer than -(으)ㄹ 게 뻔하다 and more evidence-based than a plain -(으)ㄹ 것 같다.
🔊
🎧 Iru Helper Note — Use
Korean Helper Widgets
Korean Helper Widgets to hear 비가 오나 봐요, 사람이 많은가 봐요, 문을 닫았나 봐요, 친절한가 봐요, and 학생인가 봐요. Listen for the soft “I see clues, so I infer...” feeling. 🎧
 

🌈 The Big Picture

-나 보다 and -(으)ㄴ가 보다 are Korean evidence-based conjecture patterns.
 
Use them when you notice something and then make a guess:
  • You see wet streets → “I guess it rained.”
  • You hear people laughing → “It seems fun.”
  • A restaurant is crowded → “It must be popular.”
  • Someone looks tired → “I guess they didn’t sleep.”
 
Examples:
  • 길이 젖었네요. 비가 왔나 봐요.
      • [gi-ri jeo-jeon-ne-yo. bi-ga wan-na bwa-yo] — The road is wet. I guess it rained. 🌧️
      길 = road; 젖다 = to get wet; 비 = rain.
  • 사람이 많네요. 이 식당이 유명한가 봐요.
      • [sa-ra-mi man-ne-yo. i sik-dang-i yu-myeong-han-ga bwa-yo] — There are lots of people. This restaurant seems famous. 🍽️
      식당 = restaurant; 유명하다 = to be famous.
  • 불이 꺼져 있어요. 가게가 문을 닫았나 봐요.
      • [bu-ri kkeo-jyeo i-sseo-yo. ga-ge-ga mu-neul da-dan-na bwa-yo] — The lights are off. I guess the store closed. 🏪
      불 = light; 꺼지다 = to be turned off; 문을 닫다 = to close.
 
The key feeling is: “I am not 100% sure, but the evidence points that way.” 🔎

🎨 The Core Conjecture Family

1. Action verb present + -나 보다

Use this when guessing about a current/repeated action.
  • 오다 [o-da] — to come → 오나 보다 — I guess someone is coming
  • 먹다 [meok-da] — to eat → 먹나 보다 — I guess someone is eating
  • 기다리다 [gi-da-ri-da] — to wait → 기다리나 보다 — I guess someone is waiting
 
Examples:
  • 밖이 시끄러워요. 사람들이 모이나 봐요.
      • [ba-kki si-kkeu-reo-wo-yo. sa-ram-deu-ri mo-i-na bwa-yo] — It’s noisy outside. I guess people are gathering.
  • 전화가 계속 와요. 친구가 찾나 봐요.
      • [jeon-hwa-ga gye-sok wa-yo. chin-gu-ga chat-na bwa-yo] — The phone keeps ringing. I guess a friend is looking for me.
 

2. Descriptive verb/adjective + -(으)ㄴ가 보다 or -나 보다

For adjectives, many learner grammars teach:
  • Vowel stem → ㄴ가 보다
  • Consonant stem → 은가 보다
 
Examples:
  • 바쁘다 [ba-ppeu-da] — to be busy → 바쁜가 보다 — I guess someone is busy
  • 많다 [man-ta] — to be many/much → 많은가 보다 — I guess there are many
  • 친절하다 [chin-jeol-ha-da] — to be kind → 친절한가 보다 — I guess someone is kind
 
In real speech, you will also hear adjectives with -나 보다, especially common short forms like 춥나 봐요 or 괜찮나 봐요. For this lesson, learn -(으)ㄴ가 보다 as the clean “adjective inference” pattern, and recognize -나 보다 as a common spoken alternative.
 

3. Past evidence + -았/었나 보다

Use this when guessing that something already happened.
  • 오다 → 왔나 보다 — I guess someone came
  • 먹다 → 먹었나 보다 — I guess someone ate
  • 피곤하다 → 피곤했나 보다 — I guess someone was tired
 
Examples:
  • 책상이 깨끗해요. 누가 청소했나 봐요.
      • [chaek-sang-i kkae-kkeu-tae-yo. nu-ga cheong-so-haen-na bwa-yo] — The desk is clean. I guess someone cleaned it.
  • 메시지를 안 읽었어요. 아직 못 봤나 봐요.
      • [me-si-ji-reul an il-geo-sseo-yo. a-jik mot bwan-na bwa-yo] — They didn’t read the message. I guess they haven’t seen it yet.
 

4. Noun + 인가 보다

Use 인가 보다 after nouns.
  • 학생 — student → 학생인가 보다 — I guess they are a student
  • 휴일 — holiday → 휴일인가 보다 — I guess it is a holiday
  • 문제 — problem → 문제인가 보다 — I guess it is a problem
 
Example:
  • 학교에 사람이 없네요. 오늘이 휴일인가 봐요.
      • [hak-gyo-e sa-ra-mi eom-ne-yo. o-neu-ri hyu-i-rin-ga bwa-yo] — There’s no one at school. I guess today is a holiday.

🛠️ How It Works in Sentences

-나 보다 / -(으)ㄴ가 보다 is often paired with a visible clue:
  • -네요 = “Oh, I notice...”
  • 보니까 = “seeing that...”
  • 소리를 들으니까 = “hearing the sound...”
  • 표정을 보니까 = “looking at the expression...”
 
Examples:
  • 표정을 보니까 기분이 안 좋은가 봐요.
      • [pyo-jeong-eul bo-ni-kka gi-bu-ni an jo-eun-ga bwa-yo] — Seeing the expression, I guess they are not in a good mood. 😟
  • 창문이 열려 있네요. 누가 들어왔나 봐요.
      • [chang-mu-ni yeol-lyeo in-ne-yo. nu-ga deu-reo-wan-na bwa-yo] — The window is open. I guess someone came in. 🪟
  • 계속 웃는 걸 보니까 재미있나 봐요.
      • [gye-sok un-neun geol bo-ni-kka jae-mi-in-na bwa-yo] — Seeing that they keep laughing, I guess it is fun. 😄
 
This grammar is useful because it lets you sound observant, natural, and not overly certain.

🧩 General Formation Rule

Action verbs: present

Remove 다, then add 나 보다.
  • 가다 → 가나 보다
  • 먹다 → 먹나 보다
  • 기다리다 → 기다리나 보다
  • 공부하다 → 공부하나 보다
 

Adjectives/descriptive verbs

Use -(으)ㄴ가 보다.
  • Vowel stem → ㄴ가 보다
    • 크다 → 큰가 보다
    • 바쁘다 → 바쁜가 보다
  • Consonant stem → 은가 보다
    • 많다 → 많은가 보다
    • 작다 → 작은가 보다
 

Past

Use -았/었나 보다.
  • 가다 → 갔나 보다
  • 먹다 → 먹었나 보다
  • 바쁘다 → 바빴나 보다
  • 하다 → 했나 보다
 

Nouns

Use 인가 보다.
  • 학생 → 학생인가 보다
  • 휴일 → 휴일인가 보다
  • 문제 → 문제인가 보다
✍️
Spacing note
Write the pieces separately:
  • ✅ 비가 오나 봐요
  • ✅ 사람이 많은가 봐요
  • ✅ 학생인가 봐요
  • ❌ 비가오나봐요

🚨 Nuance: Evidence-Based, but Not Fully Certain

-나 보다 / -(으)ㄴ가 보다 is not as blunt as “I know.” It often feels like:
  • “I guess from what I see/hear.”
  • “It seems that...”
  • “Apparently...”
  • “Looks like...”
 
It is especially natural when you do not have direct confirmation.
 
Compare:
  • 비가 와요. — It is raining. Direct statement.
  • 비가 오나 봐요. — I guess it is raining. Maybe I see umbrellas or hear rain. ☔
 
Because of that, avoid using it when you personally know the fact with certainty.
  • If you are looking directly at rain outside: 비가 와요.
  • If you see wet umbrellas in the hallway: 비가 오나 봐요.

🔍 -나 보다 / -(으)ㄴ가 보다 vs Related Grammar

-나 보다 / -(으)ㄴ가 보다

Evidence-based conjecture: I infer from clues.
  • 길이 젖었어요. 비가 왔나 봐요. — The road is wet. I guess it rained.
 

-(으)ㄹ 것 같다

General “I think / it seems” guess. It can be based on evidence, feeling, or opinion.
  • 비가 올 것 같아요. — I think it will rain.
 

-(으)ㄹ지도 모르다

Maybe / might. Weaker and more uncertain.
  • 비가 올지도 몰라요. — It might rain.
 

-(으)ㄹ 게 뻔하다

Strong obvious prediction. Much stronger, often critical or pessimistic.
  • 비가 오면 길이 막힐 게 뻔해요. — If it rains, the roads will obviously be jammed.
 

-아/어 보다

Try doing / experience doing. This is a completely different 보다.
  • 먹어 봐요. — Try eating it.
 

-보다 for comparison

Means “than.” Also a different 보다.
  • 오늘이 어제보다 더 추워요. — Today is colder than yesterday.

📚 Cross-check note

This lesson was checked against the existing lesson set to avoid overlap with
🔮
Strong Conjecture: -(으)ㄹ 게 뻔하다,
🌙
Vague Conjecture: -(으)ㄹ지도 모르다,
🧪
Attempting and Trying: -아/어 보다, and
⚖️
Comparison: More than: -보다 (더). This page focuses specifically on inference from evidence, not strong certainty, weak possibility, trying, or comparison. ✅

🪞 Synonym Alert

English translations depend on context:
  • “I guess...” → 피곤한가 봐요. — I guess they are tired.
  • “It seems...” → 재미있나 봐요. — It seems fun.
  • “Apparently...” → 오늘 휴일인가 봐요. — Apparently today is a holiday.
  • “Looks like...” → 비가 오나 봐요. — Looks like it is raining.
 
Useful clue words:
  • 보니까 — seeing that
  • 들으니까 — hearing that
  • 표정을 보니까 — seeing the expression
  • 분위기를 보니까 — seeing the atmosphere

⚠️ Pitfalls to Dodge

  • ❌ Using -나 보다 when you know for sure → ✅ Use a direct statement when you directly know the fact.
  • ❌ 학생나 봐요 → ✅ 학생인가 봐요.
  • ❌ 많다나 봐요 → ✅ 많은가 봐요 or spoken 많나 봐요.
  • ❌ Confusing 먹어 보다 with 먹나 보다 → 먹어 보다 = try eating; 먹나 보다 = I guess someone eats/is eating.
  • ❌ Confusing comparison 보다 with conjecture 보다 → 사과보다 = than an apple; 오나 봐요 = I guess someone is coming.
 
🎉 Now you can make careful, evidence-based guesses in Korean: 비가 왔나 봐요, 바쁜가 봐요, 학생인가 봐요. Sherlock grammar unlocked. 🔎✨
 

Try this exercise

Instructions: Choose or complete the correct evidence-based conjecture form.
1. 오다 → 밖에 사람이 있어요. 누가 ＿＿＿＿.
[o-da → ba-kke sa-ra-mi i-sseo-yo. nu-ga ＿＿＿＿]
Someone is outside. I guess someone came. 🚪
Answer
왔나 봐요 — past evidence + -았/었나 보다.
2. 많다 → 줄이 길어요. 사람이 ＿＿＿＿.
[man-ta → ju-ri gi-reo-yo. sa-ra-mi ＿＿＿＿]
The line is long. I guess there are many people. 👥
Answer
많은가 봐요.
3. 학생 → 책이 많아요. ＿＿＿＿.
[hak-saeng → chae-gi ma-na-yo. ＿＿＿＿]
There are many books. I guess they are a student. 📚
Answer
학생인가 봐요.
4. 먹다 → 접시가 비었어요. 다 ＿＿＿＿.
[meok-da → jeop-si-ga bi-eo-sseo-yo. da ＿＿＿＿]
The plate is empty. I guess they ate it all. 🍽️
Answer
먹었나 봐요.
5. 바쁘다 → 답장이 없어요. ＿＿＿＿.
[ba-ppeu-da → dap-jang-i eop-sseo-yo. ＿＿＿＿]
There is no reply. I guess they are busy. 📱
Answer
바쁜가 봐요.
6. Choose “I guess someone is waiting”:
① 기다려 봐요 / ② 기다리나 봐요
Answer
② — 기다리나 봐요 = I guess someone is waiting.
7. Choose “Please try eating”:
① 먹어 보세요 / ② 먹나 봐요
Answer
① — 먹어 보세요 = Please try eating.
8. ❌ 친구나 봐요 for “I guess they are a friend” → ✅ ＿＿＿＿
Answer
친구인가 봐요.
9. 길이 젖었어요. 비가 ＿＿＿＿.
Answer
왔나 봐요.
10. This grammar is best when:
Answer
You infer something from visible or audible evidence.
📚
Vocabulary Box
  • 오다 → to come
  • 밖 → outside
  • 사람 → person / people
  • 많다 → to be many/much
  • 줄 → line
  • 학생 → student
  • 책 → book
  • 먹다 → to eat
  • 접시 → plate
  • 바쁘다 → to be busy
  • 답장 → reply
Tip 💡 Ask: “What clue did I notice?” If there is a clue, -나 보다 / -(으)ㄴ가 보다 may fit.
🚀
Want more reps? The Practice Hub below gives you a full evidence-based conjecture workout. 🔎
 
📦
🎯 Practice Hub — Based on Evidence: -나 보다 / -(으)ㄴ가 보다
 
Welcome to the inference lab. 🔎 You’ll practice reading clues and making careful Korean guesses: sounds, expressions, empty plates, long lines, closed doors, and other evidence.
 
🔊 Audio reminder: Use
Korean Helper Widgets
Korean Helper Widgets whenever you want to hear a sentence aloud.
 

Exercise 1 — Form Builder 🔧

A. 가다 → 가＿＿＿＿
Answer
가나 봐요 — action verb present + 나 봐요.
B. 먹다 → 먹＿＿＿＿
Answer
먹나 봐요.
C. 기다리다 → 기다리＿＿＿＿
Answer
기다리나 봐요.
D. 크다 → 크＿＿＿＿
Answer
큰가 봐요.
E. 많다 → 많＿＿＿＿
Answer
많은가 봐요.
F. 바쁘다 → 바쁘＿＿＿＿
Answer
바쁜가 봐요.
G. 오다 past → ＿＿＿＿
Answer
왔나 봐요.
H. 하다 past → ＿＿＿＿
Answer
했나 봐요.
I. 학생 noun → ＿＿＿＿
Answer
학생인가 봐요.
J. 휴일 noun → ＿＿＿＿
Answer
휴일인가 봐요.
📚
Form Box
  • Action present → -나 봐요
  • Adjective vowel stem → ㄴ가 봐요
  • Adjective consonant stem → 은가 봐요
  • Past → -았/었나 봐요
  • Noun → 인가 봐요
 

Exercise 2 — Read the Clue 🔍

A. 길이 젖었어요. 비가 ＿＿＿＿.
Answer
왔나 봐요. — The road is wet, so I guess it rained.
B. 줄이 길어요. 사람이 ＿＿＿＿.
Answer
많은가 봐요.
C. 불이 꺼져 있어요. 가게가 문을 ＿＿＿＿.
Answer
닫았나 봐요.
D. 계속 웃어요. 영화가 ＿＿＿＿.
Answer
재미있나 봐요.
E. 답장이 없어요. 친구가 ＿＿＿＿.
Answer
바쁜가 봐요.
F. 신발이 많아요. 손님이 ＿＿＿＿.
Answer
많은가 봐요.
G. 표정이 안 좋아요. 기분이 ＿＿＿＿.
Answer
안 좋은가 봐요.
H. 책상이 깨끗해요. 누가 청소를 ＿＿＿＿.
Answer
했나 봐요.
I. 교실에 사람이 없어요. 수업이 ＿＿＿＿.
Answer
끝났나 봐요.
J. 가방에 책이 많아요. 학생＿＿＿＿.
Answer
학생인가 봐요.
📚
Vocabulary Box
  • 길 → road
  • 젖다 → to get wet
  • 줄 → line
  • 불이 꺼지다 → for a light to be off
  • 문을 닫다 → to close
  • 웃다 → to laugh/smile
  • 답장 → reply
  • 손님 → guest/customer
  • 표정 → facial expression
  • 청소하다 → to clean
  • 수업 → class
  • 끝나다 → to end
 

Exercise 3 — Guess, Try, Compare, or Strong? 🧠

A. “I guess they ate.”
① 먹었나 봐요 / ② 먹어 봐요
Answer
① — evidence-based guess.
B. “Please try eating.”
① 먹었나 봐요 / ② 먹어 보세요
Answer
② — trying pattern.
C. “Today is colder than yesterday.”
① 어제보다 추워요 / ② 춥나 봐요
Answer
① — comparison 보다.
D. “I guess it is cold.”
① 춥나 봐요 / ② 어제보다 추워요
Answer
① — conjecture.
E. “It is obvious they will be late.”
① 늦을 게 뻔해요 / ② 늦나 봐요
Answer
① — strong conjecture.
F. “I guess they are late.”
① 늦을 게 뻔해요 / ② 늦나 봐요
Answer
② — evidence-based inference.
G. “It might rain.”
① 비가 올지도 몰라요 / ② 비가 오나 봐요
Answer
① — weak possibility.
H. “I guess it is raining.”
① 비가 올지도 몰라요 / ② 비가 오나 봐요
Answer
② — evidence-based inference.
I. “I guess they are a student.”
① 학생인가 봐요 / ② 학생보다
Answer
① — noun + 인가 봐요.
J. “Than a student.”
① 학생인가 봐요 / ② 학생보다
Answer
② — comparison 보다.
🧭
Decision Box
  • 먹나 봐요 → I guess they eat/are eating
  • 먹어 봐요 → try eating
  • 학생보다 → than a student
  • 학생인가 봐요 → I guess they are a student
  • 늦을 게 뻔해요 → it is obvious they will be late
 

Exercise 4 — Rewrite from Clue to Inference ✍️

A. 길이 젖었어요. 비가 왔어요. → softer inference: ＿＿＿＿.
Answer
비가 왔나 봐요.
B. 사람이 많아요. 유명해요. → ＿＿＿＿.
Answer
유명한가 봐요.
C. 문이 잠겨 있어요. 집에 없어요. → ＿＿＿＿.
Answer
집에 없나 봐요.
D. 계속 하품해요. 피곤해요. → ＿＿＿＿.
Answer
피곤한가 봐요 or spoken 피곤하나 봐요.
E. 전화가 안 와요. 바빠요. → ＿＿＿＿.
Answer
바쁜가 봐요.
F. 불이 꺼져 있어요. 닫았어요. → ＿＿＿＿.
Answer
닫았나 봐요.
G. 아이가 울어요. 무서워요. → ＿＿＿＿.
Answer
무서운가 봐요.
H. 책을 많이 읽어요. 책을 좋아해요. → ＿＿＿＿.
Answer
책을 좋아하나 봐요.
I. 교복을 입었어요. 학생이에요. → ＿＿＿＿.
Answer
학생인가 봐요.
J. 눈이 빨개요. 많이 울었어요. → ＿＿＿＿.
Answer
많이 울었나 봐요.
📚
Vocabulary Box
  • 잠기다 → to be locked
  • 집 → home
  • 하품하다 → to yawn
  • 전화 → phone call
  • 아이 → child
  • 울다 → to cry
  • 무섭다 → to be scary / scared
  • 교복 → school uniform
  • 눈 → eye / snow
  • 빨갛다 → to be red
Tip 💡 Rewrite direct statements as inferences when the speaker only has clues.
 

Exercise 5 — Mixed Mastery + Pitfall Patrol 🛡️

A. ❌ 학생나 봐요 → ✅ ＿＿＿＿
Answer
학생인가 봐요.
B. ❌ 먹어 봐요 for “I guess they are eating” → ✅ ＿＿＿＿
Answer
먹나 봐요.
C. ❌ 어제보다 for “I guess it was yesterday” → ✅ ＿＿＿＿
Answer
어제였나 봐요.
D. 친구가 안 왔어요. 잊어버렸＿＿＿＿.
Answer
잊어버렸나 봐요.
E. 목소리가 작아요. 자신이 없＿＿＿＿.
Answer
자신이 없는가 봐요.
F. 가게 앞에 줄이 있어요. 맛집＿＿＿＿.
Answer
맛집인가 봐요.
G. Choose the evidence-based inference: ① 비가 왔나 봐요 / ② 비가 올 게 뻔해요
Answer
① — evidence-based inference from clues.
H. Choose the strong obvious prediction: ① 늦나 봐요 / ② 늦을 게 뻔해요
Answer
② — strong obvious prediction.
I. Choose the “try doing” sentence: ① 들어 봐요 / ② 듣나 봐요
Answer
① — 들어 봐요 = try listening.
J. -나 보다 / -(으)ㄴ가 보다 is strongest when:
Answer
The speaker has a clue and is making a careful inference, not stating a confirmed fact.
📚
Final Check
  • Action: 오나 봐요, 먹나 봐요
  • Adjective: 큰가 봐요, 많은가 봐요
  • Past: 왔나 봐요, 먹었나 봐요
  • Noun: 학생인가 봐요
  • Different pattern: 먹어 봐요 = try eating
  • Different pattern: 학생보다 = than a student
Tip 💡 Evidence first, conjecture second: clue → -나 봐요 / -(으)ㄴ가 봐요.
 
🎉 Evidence-based conjecture mastered! With -나 보다 and -(으)ㄴ가 보다, you can make smart, natural guesses from clues: 비가 왔나 봐요, 바쁜가 봐요, 학생인가 봐요. 🔎✨