In this lesson, let us take a look at how to say things like "I thought you would do it", "I didn't think you would do it", "I thought I was ...", etc.

The key structure used for this is -(으)ㄴ/ㄹ 줄 알다.

-(으)ㄴ 줄 알다 = to know/think that someone has done something
-(으)ㄹ 줄 알다 = to know/think that someone will do something

(Note that -(으)ㄴ is usually associated with the past tense and -(ㅇ)ㄹ is usually used with the future tense.)

Even though -(으)ㄴ/ㄹ 줄 알다 can be used in present tense or future tense sentences, it is mostly used in the past tense. That means the verb 알다 is mostly used in the form, 알았어요.

Let us look at some examples first.

비가 올 줄 알았어요.
= I knew it was going to rain.
= I thought it was going to rain.

사람이 많을 줄 알았어요.
= I knew there would be a lot of people.
= I thought there would be a lot of people.

How to tell whether it means "I knew" or "I thought"?
The meanings can be very different between "I knew you would like it" and "I thought you would like it". The written form for both of these in Korean is the same, but the intonation in spoken Korean is different. When you have more stress on the verb "알다", it means "I knew" and when the stress is on the -(으)ㄴ/ㄹ 줄 part, it means "I thought".

Ex)
제가 말할 줄 알았어요?
(with emphasis on 알았어요?) = Did you know that I would tell you?
(with emphasis on 말할 줄) = Did you think that I would tell you?

Ex)
어디로 갈 줄 알았어요?
(with emphasis on 알았어요?) = Did you know where he(she/they) would go?
(with emphasis on 어디로) = Where did you think he(she/they) would go?

Difference between -(으)ㄴ 줄 알다 and -(으)ㄹ 줄 알다
Basically -(으)ㄴ 줄 알다 expresses your knowledge or assumption about a PAST ACTION or a PRESENT STATE, whereas -(으)ㄹ 줄 알다 expresses your knowledge or assumption about a FUTURE action or state.

To express your knowledge or assumption about a PRESENT ACTION, you need to use -는 줄 알다.

예쁜 줄 알다
= (with emphasis on 알다) to know that something/someone is pretty
= (with emphasis on 예쁜 줄) to think that something/someone is pretty

Ex)
제 친구는 자기가 세상에서 제일 예쁜 줄 알아요.
[je chin-gu-neun ja-gi-ga se-sang-e-seo je-il ye-ppeun jun a-ra-yo.]
= My friend thinks that she is the prettiest in the world.

간 줄 알다
= (with emphasis on 알다) = to know that someone has gone somewhere
= (with emphasis on 간 줄) = to think that someone has gone somewhere

Ex)
제가 학교에 간 줄 알았어요?
= (with emphasis on 알았어요?) = Did you know that I had gone to school?
= (with emphasis on 간 줄) = Did you think that I had gone to school?


How to say "I didn't know I would ..." and "I didn't think I would ..."
For making the -(으)ㄹ 줄 알았어요 a negative sentence, there are two ways.

One is to change 알았어요 to 몰랐어요. The other is to add "안" to the original sentence.

Ex)
오늘 눈이 올 줄 알았어요.
[o-neun nu-ni ol jul a-ra-sseo-yo.]
= I knew it would snow today.
= I thought it would snow today.

→
오늘 눈이 올 줄 몰랐어요.
[o-neul nu-ni ol jul mol-la-sseo-yo.]
= I didn’t know it would snow today.

오늘 눈이 안 올 줄 알았어요.
[o-neun ni-ni an ol jul a-ra-sseo-yo.]
= I thought it would not snow today.

Sample Sentences
1. 이게 여기 있을 줄 몰랐어요.
[i-ge yeo-gi i-sseul jul mol-la-sseo-yo.]
= I didn’t know it would be here.

2. 저는 효진 씨도 올 줄 알았어요.
[jeo-neun hyo-jin ssi-do ol jul a-ra-sseo-yo.]
= I thought Hyojin would come too.

3. 이렇게 비싼 줄 몰랐어요.
[i-reo-ke bi-ssan jul mol-la-sseo-yo.]
= I didn’t know it was this expensive.

4. 저는 안 어려울 줄 알았어요.
[jeo-neun an eo-ryeo-ul jul a-ra-sseo-yo.]
= I thought it would not be difficult.

5. 제가 뭐라고 말할 줄 알았어요?
[je-ga mwo-ra-go mal-hal jul a-ra-sseo-yo?]
= What did you think I would say?