2 · Helping verbs and modal patterns
Can and cannot: -(으)ㄹ 수 있다/없다
ability and possibility
The future modifier, the noun 수 "way" and 있다 or 없다: there is a way to do it, or there is none.
The verb takes the modifier ending of the future, then comes the dependent noun 수, then 있다 or 없다. After a vowel the stem simply gains a final l: 가다 → 갈 수 있어요. After a consonant it takes -을: 먹다 → 먹을 수 있어요. A stem that already ends in l adds nothing: 만들다 → 만들 수 있어요. Irregular stems change as usual: 듣다 → 들을 수, 돕다 → 도울 수. Because 수 is a noun, the pattern is written as three words.
수 means "way, means", so 갈 수 있어요 is literally "there is a way to go". That covers both what English splits between "can" and "be able to": ability (수영할 수 있어요, "I can swim") and possibility in the circumstances (여기에서 표를 살 수 있어요, "you can buy tickets here"). 없다 takes the way away: 갈 수 없어요, "I can't go". The past goes on 있다 or 없다: 갈 수 있었어요, 갈 수 없었어요.
In conversation, "I can't make it" is more often the short negation 못 가요. -을 수 없다 is more explicit and firmer, which is why it is the form of rules, notices and careful writing: 이곳에서는 사진을 찍을 수 없습니다. With the particle 도 the pattern softens into a possibility: 늦을 수도 있어요, "I might be late".
The common slips are dropping a piece: 가 수 있어요 without the modifier, or 갈 있어요 without 수. Both leave the verb with nothing to attach to. For skills that have to be learnt — swimming, driving, an instrument — Korean also has -을 줄 알다, "know how to", which is the next topic.
The form
| after a vowel | 가다 → 갈 수 있어요 |
| after a consonant | 먹다 → 먹을 수 있어요 |
| stem ending in l | 만들다 → 만들 수 있어요 |
| cannot | 갈 수 없어요 |
| could (past) | 갈 수 있었어요 |
| might | 갈 수도 있어요 |
The rules one by one
The form this topic is about
After a consonant the stem takes -을; after a vowel it gains a final l; a stem in l adds nothing.
매운 음식도 먹을 수 있어요.I can eat spicy food too.
Use 없다 for "cannot", and put the past on 있다 or 없다.
어제는 바빠서 갈 수 없었어요.I was busy yesterday, so I couldn't go.
수도 있다 says that something might happen.
길이 막히면 조금 늦을 수도 있어요.If the traffic is bad, I might be a little late.
In notices and rules, -을 수 없습니다 states what is not possible or not allowed.
이곳에서는 담배를 피울 수 없습니다.You cannot smoke here.
A closer look
Can, may and might
English spreads three ideas over "can", "may" and "might". Korean uses this pattern for ability and for possibility, but asks permission with a different one: 여기 앉아도 돼요?, "may I sit here?". 여기 앉을 수 있어요? asks whether sitting there is possible at all — whether the chair is free or strong enough — not whether you are allowed to.
The noun 수 can take particles like any other noun. 수도 makes a possibility, 수는 sets up a contrast (갈 수는 있지만, "I could go, but …"), and 수가 stresses that there really is no way: 너무 아파서 걸을 수가 없어요.
How to spot it
- -(으)ㄹ 수 있다
- -(으)ㄹ 수 없다
- -(으)ㄹ 수도 있다
- 수
Example sentences
저는 한국어로 간단한 이메일을 쓸 수 있어요.I can write a simple email in Korean.
이 방에서는 바다를 볼 수 있어요.You can see the sea from this room.
지금은 전화를 받을 수 없어요.I cannot answer the phone right now.
비행기표가 비싸서 고향에 갈 수 없었어요.The plane tickets were expensive, so I couldn't go home.
누구나 실수할 수 있어요.Anyone can make a mistake.
혹시 내일 일찍 올 수 있어요?Could you possibly come early tomorrow?
8 more example sentences
주말에는 늦게까지 잘 수 있어요.At weekends I can sleep in.
이 문제는 혼자 풀 수 없어요.I can't solve this problem on my own.
여기에서 표를 살 수 있어요?Can I buy a ticket here?
너무 시끄러워서 아무 소리도 들을 수 없었어요.It was so noisy that I couldn't hear a thing.
그 사람은 외국어를 세 개나 할 수 있어요.That person can speak as many as three foreign languages.
내일은 비가 올 수도 있어요.It might rain tomorrow.
이 가방은 가벼워서 아이도 들 수 있어요.This bag is light enough for a child to carry.
어떻게 하면 한국어를 빨리 배울 수 있을까요?How can I learn Korean quickly?
Worth knowing (1)
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수가 없다: "simply cannot"
Adding 가 to 수 makes the impossibility stronger, as if every way had been tried. It is common when something is beyond your control.
배가 너무 아파서 걸을 수가 없어요.My stomach hurts so much I cannot walk.
The trap English speakers fall into
Watch out
수 is a noun, and a verb can only stand in front of a noun in a modifier form. Without the final l of 칠, nothing joins the verb to 수.
Verb plus -(eu)l su itda: "there is a way to"; swap itda for eopda and the way is gone.
Your turn
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