Can/Cannot
Expressing ability and inability with -(으)ㄹ 수 있다/없다
I can express ability and inability using -(으)ㄹ 수 있다/없다 and 못
Look at these examples. Can you spot the grammar pattern?
한국어를 할 수 있어요.
I can speak Korean.
매운 음식을 못 먹어요.
I can't eat spicy food.
여기에서 수영할 수 있어요?
Can I swim here?
내일 올 수 없어요.
I can't come tomorrow.
Pay attention to the highlighted parts. What do they have in common?
-(으)ㄹ 수 있다/없다 (Can/Cannot)
Express ability or possibility using -(으)ㄹ 수 있다 (can) and -(으)ㄹ 수 없다 (cannot).
| Stem ending | Form | Example |
|---|---|---|
| Vowel/ㄹ | -ㄹ 수 있다 | 하다 → 할 수 있어요 (can do) |
| Consonant | -을 수 있다 | 먹다 → 먹을 수 있어요 (can eat) |
| Positive (can) | Negative (cannot) |
|---|---|
| 한국어를 할 수 있어요 | 한국어를 할 수 없어요 |
| I can speak Korean | I can't speak Korean |
Alternative negative: verb stem + -ㄹ/을 수 없다 OR 못 + verb: 못 먹어요 = 먹을 수 없어요 (can't eat). 못 is shorter and more common in speech.
수 literally means "way/means" — so -(으)ㄹ 수 있다 literally means "the way to [verb] exists."
Mix up -(으)ㄹ 수 있다 with 못. Confuse ability with permission.
Common Error Patterns
Used -(으)ㄹ 수 있다 for permission instead of -아/어도 되다
-(으)ㄹ 수 있다 = ability/possibility. -아/어도 되다 = permission
Wrong -(으)ㄹ form for stem type
Vowel/ㄹ stem → -ㄹ 수, consonant stem → -을 수
한국어를 할 수 있어요.
I can speak Korean.
하다 → 할 수 있어요. 하 (vowel stem) + -ㄹ 수 있어요.
매운 음식을 못 먹어요.
I can't eat spicy food.
못 + 먹어요 = can't eat. Short negation form (못) is common in daily speech.
여기에서 수영할 수 있어요?
Can I swim here?
수영하다 → 수영할 수 있어요? Can also mean 'Is it possible to swim here?'
내일 올 수 없어요.
I can't come tomorrow.
오다 → 올 수 없어요. 오 (vowel) + -ㄹ 수 없어요 (cannot).
Practice in course
Apply this grammar in A1 course exercises
Put it into practice
Try a free exercise from the courseFrequently asked questions
- When is -(으)ㄹ 수 있다/없다 used?
- Express ability or possibility using -(으)ㄹ 수 있다 (can) and -(으)ㄹ 수 없다 (cannot).
- How is -(으)ㄹ 수 있다/없다 formed?
- Alternative negative: verb stem + -ㄹ/을 수 없다 OR 못 + verb: 못 먹어요 = 먹을 수 없어요 (can't eat). 못 is shorter and more common in speech. 수 literally means "way/means" — so -(으)ㄹ 수 있다 literally means "the way to [verb] exists."
- What are common mistakes with -(으)ㄹ 수 있다/없다?
- Mixing up -(으)ㄹ 수 있다 with 못. Forgetting vowel harmony in the -(으)ㄹ ending. Confusing ability with permission. EN speakers: English 'can' covers both ability and permission — Korean separates these. -(으)ㄹ 수 있다 = ability, -아/어도 되다 = permission. DE speakers: German 'können' also covers ability + permission. Same confusion risk as English. Modal verb position differs — German puts modal at end (Ich kann Koreanisch sprechen) while Korean embeds it mid-phrase. RU speakers: Russian 'мочь' maps well. The -(으)ㄹ suffix is similar in concept to Russian potential forms. Main issue: choosing between 못 and -(으)ㄹ 수 없다.