When learning Korean, it’s essential to understand the subtle differences between expressions like ‘(으)ㄹ 줄 알다/모르다’ and ‘(으)ㄹ 수 있다.’ These two structures might seem similar, but they are used in different contexts. In this complete guide, we’ll break down their meanings, usages, and provide clear examples to help you master these important expressions. Whether you’re a beginner or looking to refine your Korean skills, understanding these differences will make your conversations much more accurate.
Contents
1. Definition
- (으)ㄹ 줄 알다/모르다: To know/not know how to do something (having the knowledge or skill)
- English equivalent: “to know how to / not know how to”
- (으)ㄹ 수 있다: To be able to do something (having the capability or possibility)
- English equivalent: “can / cannot”
- English equivalent: “can / cannot”
2. Form (Structure)
| Expression | Structure | Example |
| (으)ㄹ 줄 알다/모르다 | Verb stem + (으)ㄹ 줄 알다/모르다 | 먹다 → 먹을 줄 알아요 (I know how to eat.) 가다 → 갈 줄 알아요 |
| (으)ㄹ 수 있다 | Verb stem + (으)ㄹ 수 있다 | 먹다 → 먹을 수 있어요 (I can eat.) 가다 → 갈 수 있어요 (I can go.) |
3. Meaning & Usage
The expressions ‘(으)ㄹ 줄 알다/모르다’ and ‘(으)ㄹ 수 있다’ may seem similar but serve different purposes in Korean. Below, we’ll explore their meanings and usage with clear examples.
(으)ㄹ 줄 알다/모르다
This expression is used to talk about the ability to do something or knowledge of how to do something. It emphasizes knowing or not knowing how to perform an action, rather than just being able to do it.
- Meaning: “To know how to” or “not know how to” do something.
- Usage: Used when you are referring to your knowledge or ability to do something based on skill or experience.
Examples:
- 음악을 잘 할 줄 알아요. (I know how to play music.)
- 한국어를 읽을 줄 알아요. (I know how to read Korean.)
- 이 문제를 풀 줄 몰라요. (I don’t know how to solve this problem.)
- 운전을 할 줄 알지만 자주 하지는 않아요. (I know how to drive, but I don’t do it often.)
- 이 기계를 사용할 줄 몰라요. (I don’t know how to use this machine.)
(으)ㄹ 수 있다
This structure expresses the physical or situational ability to do something. It is not about knowledge or skill but rather about the possibility or capacity to perform an action.
- Meaning: “To be able to” do something (physical or situational ability).
- Usage: Used when referring to the capability of performing an action, whether it be physical, situational, or external.
Examples:
- 이 문제를 풀 수 있어요. (I can solve this problem.)
- 저는 영어를 할 수 있어요. (I can speak English.)
- 운전할 수 있어요. (I can drive.)
- 그는 아침 일찍 일어날 수 있어요. (He can wake up early in the morning.)
- 내가 도와줄 수 있어요. (I can help you.)
4. Key Points to Remember
- (으)ㄹ 줄 알다: Knowing how to do something (knowledge or skill)
- (으)ㄹ 수 있다: Being able to do something (capability or possibility)
5. Practice Exercises
- 저는 한국어를 ____ 알아요, 하지만 아직 유창하게 ____ 없어요.
(I know how to speak Korean, but I can’t speak it fluently yet.) - 그녀는 피아노를 ____ 알지만, 오늘은 손가락 부상 때문에 ____ 없어요.
(She knows how to play the piano, but she can’t play today because of a finger injury.) - 당신은 수영을 ____ 아세요? 그리고 깊은 물에서 ____ 있나요?
(Do you know how to swim? And can you swim in deep water?) - 저는 컴퓨터를 ____ 몰라서 이메일을 ____ 없어요.
(I don’t know how to use a computer, so I can’t send an email.) - 그는 요리를 ____ 알아요. 특히 파스타를 잘 ____ 있어요.
(He knows how to cook. Especially, he can make pasta well.) - 우리 팀은 이 프로젝트를 ____ 알지만, 시간이 부족해서 내일까지 ____ 없어요.
(Our team knows how to complete this project, but we can’t finish it by tomorrow because of a lack of time.) - 그녀는 3개 국어로 ____ 알아요. 덕분에 외국인과 쉽게 대화를 ____ 있어요.
(She knows how to speak three languages, so she can easily have conversations with foreigners.) - 저는 기타를 ____ 몰라요. 하지만 노래는 ____ 있어요.
(I don’t know how to play the guitar, but I can sing.) - 그들은 스키를 ____ 알아요. 그래서 겨울에 자주 스키를 ____ 있어요.
(They know how to ski, so they can often go skiing in winter.) - 당신은 이 기계를 ____ 아세요? 고장 났는데 ____ 있나요?
(Do you know how to fix this machine? It’s broken—can you repair it?)
6. Answers
- 말할 줄 / 말할 수
- 칠 줄 / 칠 수
- 할 줄 / 수영할 수
- 사용할 줄 / 보낼 수
- 할 줄 / 만들 수
- 완성할 줄 / 끝낼 수
- 말할 줄 / 나눌 수
- 칠 줄 / 부를 수
- 탈 줄 / 탈 수
- 고칠 줄 / 고칠 수
7. Common Mistakes and Tips
⚠️ Mistake 1: Confusing ‘(으)ㄹ 줄 알다’ with ‘(으)ㄹ 수 있다’
Incorrect: 저는 피아노를 칠 수 있어요. ❌ (when meaning “I know how to play the piano.”)
Correct: 저는 피아노를 칠 줄 알아요. ✅ (I know how to play the piano.)
Also correct: 저는 피아노를 칠 수 있어요. ✅ (I can play the piano. / I am able to play the piano.)
💡 Tip: Use ‘(으)ㄹ 줄 알다’ when expressing knowledge of how to do something, and ‘(으)ㄹ 수 있다’ for expressing capability or possibility.
⚠️ Mistake 2: Misusing ‘(으)ㄹ 줄 알다’ for immediate physical ability
Incorrect: 저는 지금 무거운 짐을 들 줄 알아요. ❌ (when meaning “I can lift heavy luggage now.”)
Correct: 저는 지금 무거운 짐을 들 수 있어요. ✅ (I can lift heavy luggage now.)
💡 Tip: Use ‘(으)ㄹ 줄 알다’ for learned skills or knowledge, and ‘V으)ㄹ 수 있다’ for immediate physical ability or situational possibility.
⚠️ Mistake 3: Using ‘(으)ㄹ 수 있다’ when referring to lack of skill
Incorrect: 저는 영어를 할 수 없어요. ❌
(when meaning “I don’t know how to speak English.”)
Correct: 저는 영어를 할 줄 몰라요. ✅
(I don’t know how to speak English.)
Also correct: 저는 영어를 할 수 없어요. ✅
(I can’t speak English due to a specific reason, like a physical or situational limitation.)
💡 Tip: Use ‘(으)ㄹ 줄 몰라요’ to express the lack of knowledge or skill, and ‘(으)ㄹ 수 없다’ for physical or situational inability.
⚠️ Mistake 4: Misunderstanding the use of ‘(으)ㄹ 수 있다’ for future possibilities
Correct: 내일은 시간이 있을 수 있어요. ✅
(I might have time tomorrow. / It’s possible that I’ll have time tomorrow.)
Also correct: 내일은 시간이 있을 거예요. ✅
(I will have time tomorrow. / I expect to have time tomorrow.)
💡 Tip:
- Use ‘(으)ㄹ 수 있다’ to express possibility or potential in the future. It indicates that something might happen, but it’s not certain.
- Use ‘(으)ㄹ 거예요’ to express a stronger prediction or expectation about the future.
Example:
- 내일은 비가 올 수 있어요. (It might rain tomorrow.)
- 내일은 비가 올 거예요. (It will rain tomorrow. / I expect it to rain tomorrow.)
The choice between these two expressions depends on how certain you are about the future
⚠️ Mistake 5: Using ‘(으)ㄹ 줄 알다’ in future contexts
Incorrect: 내일은 이 일을 할 줄 알아요. ❌ (when meaning “I can do this task tomorrow.”)
Correct: 내일은 이 일을 할 수 있어요. ✅ (I can do this task tomorrow.)
💡 Tip: ‘(으)ㄹ 줄 알다’ refers to knowing how to do something, and should not be used for expressing future actions. Use ‘(으)ㄹ 수 있다’ for future capabilities.
Understanding the difference between ‘(으)ㄹ 줄 알다’ and ‘(으)ㄹ 수 있다’ is crucial for Korean learners. Mastering their correct usage will help you communicate more clearly and naturally.