HYEJU LANGUAGE LAB · INTERMEDIATE 32 · LESSON 117

-(으)ㄴ/는 줄 알았다 / 몰랐다I thought… / I didn’t know that…

-(으)ㄴ/는 줄 알았다 usually means “I thought… (but I was wrong)”: 학생인 줄 알았어요 (I thought you were a student). -(으)ㄴ/는 줄 몰랐다 means “I didn’t know that…”: 오늘이 생일인 줄 몰랐어요 (I didn’t know today was your birthday).

Listening speed

Listen buttons use your device’s Korean voice. A Korean voice must be installed and available to the browser.

A situation you already know

You find out your new coworker is actually ten years older than you.

저보다 어린 줄 알았어요!

I thought you were younger than me!

You believed one thing, and it turned out to be wrong. 줄 알았어요 carries that surprise.

Build the form

FORM IN MOTION

Try an expression

어리다 → 어리 + ㄴ 줄 알았다 → 어린 줄 알았어요Complete expression
오다 → 오 + 는 줄 알았다 → 오는 줄 알았어요Complete expression
가다 (이미) → 가 + ㄴ 줄 알았다 → 간 줄 알았어요Complete expression
학생 → 학생 + 인 줄 알았다 → 학생인 줄 알았어요Complete expression
어렵다 (예상) → 어려우 + ㄹ 줄 몰랐다 → 어려울 줄 몰랐어요Complete expression

Adjectives: -(으)ㄴ 줄 → 어린 줄, 바쁜 줄, 좋은 줄.
Verbs happening at that time: -는 줄 → 오는 줄, 자는 줄. Already happened: -(으)ㄴ 줄 → 간 줄, 먹은 줄.
Something you didn’t expect beforehand: -(으)ㄹ 줄 → 이렇게 어려울 줄 몰랐어요.
Nouns: 인 줄 → 학생인 줄, 한국 사람인 줄.
Usually in the past: 알았어요 / 몰랐어요. Put a space before 줄.
Careful: V-(으)ㄹ 줄 알다 in the present means ability: 수영할 줄 알아요 (Lesson 39).

Think in Korean · an English-speaker’s guide

English “I thought you were…” already hints that the belief was wrong; 줄 알았어요 works the same way.
줄 몰랐어요 is handy for surprises and apologies: 이렇게 늦은 줄 몰랐어요 (I didn’t realize it was so late).
Choose the modifier by the time of what you thought: 자는 줄 (was sleeping then) vs 잔 줄 (had gone to sleep).

Six examples in context

오늘이 휴일인 줄 알았어요.

I thought today was a holiday.

민수 씨가 벌써 집에 간 줄 알았어요.

I thought Minsu had already gone home.

이렇게 늦은 줄 몰랐어요. 미안해요.

I didn’t realize it was this late. Sorry.

그 사람이 한국 사람인 줄 알았어요.

I thought that person was Korean.

시험이 이렇게 어려울 줄 몰랐어요.

I didn’t expect the exam to be this hard.

동생이 자는 줄 알고 조용히 들어갔어요.

I thought my sibling was asleep, so I went in quietly.

Compare with related patterns

-(으)ㄹ 줄 알다 (ability)

운전할 줄 알아요.

“I can drive.” Ability, in the present (Lesson 39).

-(으)ㄴ/는 것 같았다

학생인 것 같았어요.

“He seemed to be a student.” A guess, without the feeling that you were wrong (Lesson 74).

-다고 생각했다

학생이라고 생각했어요.

“I thought he was a student.” Neutral thinking; 줄 알았어요 strongly suggests you were mistaken.

Pattern	Choose it when…
-(으)ㄴ/는 줄 알았다	I thought… (and I was wrong)
-(으)ㄴ/는/(으)ㄹ 줄 몰랐다	I didn’t know / didn’t expect…
-(으)ㄹ 줄 알다 (present)	know how to / can
-다고 생각했다	a neutral “I thought”

Common mistakes

학생 줄 알았어요.학생인 줄 알았어요.

Nouns need 인.

바쁘는 줄 몰랐어요.바쁜 줄 몰랐어요.

Adjectives take -(으)ㄴ.

늦은줄 몰랐어요.늦은 줄 몰랐어요.

Put a space before 줄.

저는 수영할 줄 알았어요. (= 지금 수영을 할 수 있어요.)저는 수영할 줄 알아요.

For ability, use the present 알아요.

Mini practice · six questions

Try each one before opening the answer. Translation answers are models; other natural wording is possible.

Fill in the blank오늘이 ______ 줄 알았어요. 아직 목요일이네요. (금요일)
Check answer
오늘이 금요일인 줄 알았어요. 아직 목요일이네요.
Noun → 인 줄.
Fill in the blank이 식당이 이렇게 ______ 줄 몰랐어요. (맛있다)
Check answer
이 식당이 이렇게 맛있는 줄 몰랐어요.
있다 type → -는 줄.
Choose the natural form친구가 벌써 (떠난 / 떠나는) 줄 알았는데 아직 있었어요.
Check answer
떠난
You thought it had already happened → -(으)ㄴ 줄.
Choose the natural form저는 기타를 (칠 줄 알아요 / 친 줄 알아요).
Check answer
칠 줄 알아요
Ability → -(으)ㄹ 줄 알다 (present).
Fix the mistake그 사람이 의사 줄 알았어요.
Check answer
그 사람이 의사인 줄 알았어요.
Noun → 인 줄.
Say it in KoreanI didn’t know you were Japanese.
Check answer
일본 사람인 줄 몰랐어요.
Noun → 인 줄 몰랐어요.

Today’s key point

I thought (wrongly): -(으)ㄴ/는 줄 알았다. I didn’t know / expect: -(으)ㄴ/는/(으)ㄹ 줄 몰랐다. Adjectives -(으)ㄴ, verbs -는 / -(으)ㄴ, unexpected future -(으)ㄹ, nouns 인. Present -(으)ㄹ 줄 알다 = ability.

Keep learning

Hyeju Yoo

M.A. in Korean Language Education · Certified Korean language teacher

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