Korean Pattern ~(으)ㄹ 수 있다/없다: How to Say "can / cannot"
Verb stem + (으)ㄹ 수 있다/없다. Use 을 after consonant, ㄹ after vowel.
Category: Sentence Patterns
The Rule
The pattern ~(으)ㄹ 수 있다/없다 (eul su itda/eopda) expresses ability or possibility in Korean, directly equivalent to 'can' or 'cannot' in English. This is one of the most essential grammar patterns you will learn because it allows you to talk about what you are capable of doing and what is impossible. The formation depends on whether the verb stem ends in a vowel or consonant. If the stem ends in a vowel, add ㄹ 수 있다: 가다 becomes 갈 수 있다 (gal su itda, can go). If the stem ends in a consonant, add 을 수 있다: 먹다 becomes 먹을 수 있다 (meogeul su itda, can eat). The word 수 literally means 'way' or 'method,' so the pattern literally translates to 'there is a way to do X.' For the negative (cannot), simply replace 있다 with 없다: 갈 수 없다 (gal su eopda, cannot go). This pattern covers both physical ability and situational possibility, making it extremely versatile in everyday conversation.
Why English Speakers Get It Wrong
English speakers struggle with ~(으)ㄹ 수 있다 for several interconnected reasons. First, English uses a single modal verb 'can' that sits before the main verb, while Korean attaches a multi-part ending after the verb stem. This structural difference means learners must completely reverse their thinking about word order. Second, English 'can' covers both ability and permission, but Korean has separate patterns for each: ~(으)ㄹ 수 있다 for ability and ~아/어도 되다 for permission. Saying 여기서 사진 찍을 수 있어요 might mean 'I am physically able to take photos here,' while 여기서 사진 찍어도 돼요 means 'Am I allowed to take photos here?' Third, the vowel-consonant distinction (ㄹ vs 을) trips up many learners who forget to check the final consonant of the verb stem. Fourth, English speakers often confuse ~(으)ㄹ 수 있다 with 못하다, which is the short-form negation for inability. While 못 먹어요 and 먹을 수 없어요 both mean 'cannot eat,' they carry slightly different nuances — 못 suggests inability due to circumstances, while 수 없다 is more neutral and formal.
Formation Rules Step by Step
Mastering the formation requires understanding the vowel-consonant rule clearly. Step 1: Identify your verb and remove 다 to find the stem. 보다 (to see) becomes 보, 읽다 (to read) becomes 읽. Step 2: Check if the stem ends in a vowel or consonant. 보 ends in the vowel ㅗ. 읽 ends in the consonant ㄱ. Step 3: Apply the correct form. Vowel-ending stems get ㄹ 수 있다: 보 + ㄹ 수 있다 = 볼 수 있다 (bol su itda). Consonant-ending stems get 을 수 있다: 읽 + 을 수 있다 = 읽을 수 있다 (ilgeul su itda). Special case: stems already ending in ㄹ simply add 수 있다 without doubling: 만들다 → 만들 수 있다 (mandeul su itda). For conjugation, modify 있다/없다 into the appropriate speech level: 있어요/없어요 (polite), 있습니다/없습니다 (formal), 있어/없어 (casual). Past tense ability uses 을 수 있었다: 갈 수 있었어요 (was able to go). This pattern is remarkably regular with very few exceptions, making it reliable once you understand the formation rule.
Ability vs. Permission vs. Possibility
Korean distinguishes between different types of 'can' more precisely than English does, and understanding these distinctions is essential for natural-sounding Korean. Physical or learned ability: 수영할 수 있어요 (suyeonghaleul su isseoyo, I can swim — I have the skill). Situational possibility: 오늘 만날 수 있어요 (oneul mannal su isseoyo, We can meet today — it is possible given the circumstances). For permission, Korean prefers ~아/어도 되다: 여기 앉아도 돼요? (yeogi anjado dwaeyo?, May I sit here?). Using ~(으)ㄹ 수 있어요 for permission sounds odd to Korean ears — it implies you are asking about physical capability rather than social permission. Another related pattern is ~(으)ㄹ 줄 알다, which specifically means 'know how to' through learned skill: 피아노를 칠 줄 알아요 (pianoreul chil jul arayo, I know how to play piano). While 칠 수 있어요 also works, 칠 줄 알아요 emphasizes the learned nature of the skill. Being able to choose the right 'can' pattern shows sophistication in your Korean ability.
못 vs. ~(으)ㄹ 수 없다
Korean has two ways to express 'cannot,' and choosing between them reveals your level of Korean sophistication. The short form 못 (mot) is placed directly before the verb: 못 가요 (mot gayo, cannot go), 못 먹어요 (mot meogeoyo, cannot eat). This form is more colloquial and often implies external circumstances preventing the action. The long form ~(으)ㄹ 수 없다 is more formal and neutral: 갈 수 없어요 (gal su eopseoyo, cannot go), 먹을 수 없어요 (meogeul su eopseoyo, cannot eat). In conversation, 못 is overwhelmingly more common. However, in writing, formal speeches, and when you want to sound more measured, ~(으)ㄹ 수 없다 is preferred. There is also a subtle emotional difference: 시험에 못 갔어요 often implies regret or frustration, while 시험에 갈 수 없었어요 sounds more matter-of-fact. For 하다 verbs, 못 is placed between the noun and 하다: 운동 못 해요 (undong mot haeyo), not 못 운동해요. This split placement rule for 하다 verbs is a common source of errors for learners.
Combining with Other Patterns
The ~(으)ㄹ 수 있다 pattern combines beautifully with other Korean grammar structures to create nuanced expressions. With ~(으)면 (if/when): 시간이 있으면 갈 수 있어요 (sigani isseumyeon gal su isseoyo, If I have time, I can go). With ~는데 (but/background): 한국어를 읽을 수 있는데 쓸 수 없어요 (hangugeoreul ilgeul su inneunde sseul su eopseoyo, I can read Korean but cannot write it). With ~아/어서 (because): 한국어를 할 수 있어서 좋아요 (hangugeoreul hal su isseoseo joayo, It's great that I can speak Korean). With ~고 싶다 (want to): 할 수 있으면 하고 싶어요 (hal su isseumyeon hago sipeoyo, If I can, I want to do it). With ~기 때문에 (because): 운전할 수 없기 때문에 버스를 탔어요 (unjeonhal su eopgi ttaemune beoseureul tasseoyo, Because I cannot drive, I took the bus). These combinations are where Korean truly comes alive, allowing you to express complex ideas about ability, conditions, and desires in a single flowing sentence.
Real-World Conversation Examples
In daily Korean life, ~(으)ㄹ 수 있다/없다 appears constantly across all types of interactions. At a restaurant: 매운 음식 먹을 수 있어요? (maeun eumsik meogeul su isseoyo?, Can you eat spicy food?). At work: 내일까지 끝낼 수 있어요 (naeilkkaji kkeutnaeil su isseoyo, I can finish by tomorrow). Making plans: 토요일에 만날 수 있어요? (toyoire mannal su isseoyo?, Can we meet on Saturday?). Describing skills on a resume: 영어와 일본어를 할 수 있습니다 (yeongeowa ilboneoreul hal su itseumnida, I can speak English and Japanese). In K-dramas, the emotional 나 없이 살 수 있어? (na eopsi sal su isseo?, Can you live without me?) is a classic line. When shopping: 카드로 결제할 수 있어요? (kadeuro gyeoljehal su isseoyo?, Can I pay by card?). Notice how the pattern adapts to every context while maintaining the same grammatical structure — verb stem + (으)ㄹ 수 있다/없다. This consistency makes it one of the most reliable patterns to master.
Questions and Answers with This Pattern
Forming questions with ~(으)ㄹ 수 있다 is essential for daily communication. In Korean, turning a statement into a question often requires only a change in intonation (in speech) or a question mark (in writing) for polite forms. Statement: 한국어를 할 수 있어요 (I can speak Korean). Question: 한국어를 할 수 있어요? (Can you speak Korean?). For formal questions, add -까: 참석할 수 있습니까? (chamseokhal su itseumnikka?, Are you able to attend?). Answering yes: 네, 할 수 있어요 (ne, hal su isseoyo, Yes, I can). Answering no: 아니요, 할 수 없어요 (aniyo, hal su eopseoyo, No, I cannot). A softer refusal: 좀 어려울 것 같아요 (jom eoryeoul geot gatayo, I think it might be difficult). Koreans often avoid direct 'no' answers, so learning indirect refusals alongside the grammar pattern is culturally important. Practice creating question-answer pairs with various verbs to build conversational fluency. The question form is especially useful when traveling in Korea, asking about services, or checking someone's availability.
Common Mistakes and How to Fix Them
Learners consistently make several predictable errors with this pattern. Mistake 1: Forgetting the vowel/consonant rule. Wrong: 먹ㄹ 수 있어요. Correct: 먹을 수 있어요. Always check the final consonant of the stem. Mistake 2: Using this pattern for permission instead of ~아/어도 되다. While technically understood, it sounds unnatural for permission contexts. Mistake 3: Placing 못 incorrectly with 하다 verbs. Wrong: 못 공부해요. Correct: 공부 못 해요 (gongbu mot haeyo). The 못 goes between the noun and 하다. Mistake 4: Confusing ~(으)ㄹ 수 있다 with ~(으)ㄹ 줄 알다. The former is about ability/possibility, the latter specifically about learned skills. Mistake 5: Forgetting that ㄹ-irregular stems do not double the ㄹ. 살다 → 살 수 있다, not 살ㄹ 수 있다. Being aware of these common pitfalls allows you to self-correct more quickly and build accurate habits from the start. Review your own writing for these specific errors regularly.
Practice and Reinforcement
Effective practice requires both structured exercises and real-world application. Exercise 1: Convert these verbs into 'can' and 'cannot' forms — 하다 (do), 보다 (see), 쓰다 (write), 만들다 (make), 운전하다 (drive). Exercise 2: Answer these questions using the pattern — 한국 음식 만들 수 있어요? 수영할 수 있어요? 기타 칠 수 있어요? Exercise 3: Create sentences distinguishing ability from permission — use both ~(으)ㄹ 수 있다 and ~아/어도 되다 for the same scenarios. Exercise 4: Write a self-introduction paragraph describing five things you can do and three things you cannot do. Exercise 5: Practice the short negation 못 with five 하다 verbs, remembering the split placement rule. For maximum retention, try the 'ability diary' method: each evening, write three things you were able to do today and one thing you could not do, all in Korean using this pattern. This daily practice connects grammar to your personal experiences, making it stick in long-term memory.
Examples
한국어를 할 수 있어요. — hangugeoreul hal su isseoyo. — I can speak Korean.
매운 음식 먹을 수 있어요? — maeun eumsik meogeul su isseoyo? — Can you eat spicy food?
내일 만날 수 있어요. — naeil mannal su isseoyo. — We can meet tomorrow.
여기서 사진 찍을 수 있어요? — yeogiseo sajin jjigeul su isseoyo? — Can I take photos here?
운전할 수 없어요. — unjeonhal su eopseoyo. — I cannot drive.
피아노를 칠 수 있어요. — pianoreul chil su isseoyo. — I can play the piano.
지금은 갈 수 없어요. — jigeumeun gal su eopseoyo. — I can't go right now.
카드로 결제할 수 있어요? — kadeuro gyeoljehal su isseoyo? — Can I pay by card?
Common Mistakes
Incorrect: 먹ㄹ 수 있어요. → Correct: 먹을 수 있어요.. Consonant-ending stems need 을, not just ㄹ.
Incorrect: 못 공부해요. → Correct: 공부 못 해요.. With 하다 verbs, 못 goes between the noun and 하다.
Incorrect: 여기 앉을 수 있어요? → Correct: 여기 앉아도 돼요?. For permission, use ~아/어도 되다 instead.
Incorrect: 살ㄹ 수 있어요. → Correct: 살 수 있어요.. ㄹ-ending stems don't double the ㄹ.
Incorrect: 할 수 있다 피아노를. → Correct: 피아노를 칠 수 있어요.. Object comes before the verb in Korean word order.
Quiz
How do you say 'I can swim' in polite Korean?
What is the correct negative form?
For permission, which pattern is more appropriate?