Ability and possibility

Korean expresses ability or possibility with -(으)ㄹ 수 있어요. It means “can”, “be able to”, or “it is possible to”. This pattern is extremely important because it lets you talk about skills, permission-like possibility, and practical ability.

The structure is Verb stem + -(으)ㄹ 수 있어요. Use 을 수 있어요 after a verb stem ending in a final consonant, and ㄹ 수 있어요 after a verb stem ending in a vowel. For example, 먹다 becomes 먹을 수 있어요, and 가다 becomes 갈 수 있어요.

The word 수 means something like “way / possibility / ability”. So the literal feeling of 갈 수 있어요 is “there is a way to go” or “the possibility to go exists.” In natural English, it simply becomes “can go”.

For learners living in Korea, this pattern is essential. You can say 한국어를 할 수 있어요 meaning “I can speak Korean”, 운전할 수 있어요 meaning “I can drive”, or 오늘 갈 수 있어요 meaning “I can go today.”

The choice between ㄹ 수 있어요 and 을 수 있어요 depends on whether the verb stem ends in a vowel or a final consonant. This is the same kind of sound-based choice you have already seen with other Korean endings.

If the verb stem ends in a vowel, attach ㄹ 수 있어요. 가다 becomes 갈 수 있어요, 보다 becomes 볼 수 있어요, and 마시다 becomes 마실 수 있어요.

If the verb stem ends in a final consonant, attach 을 수 있어요. 먹다 becomes 먹을 수 있어요, 읽다 becomes 읽을 수 있어요, and 앉다 becomes 앉을 수 있어요.

There is one useful exception to remember early: verb stems ending in ㄹ usually drop nothing and simply use 수 있어요 after the ㄹ sound. For example, 살다 becomes 살 수 있어요, meaning “can live”.

To say that you cannot do something, replace 있어요 with 없어요: -(으)ㄹ 수 없어요. This means “cannot”, “be unable to”, or “there is no way to do it”.

For example, 갈 수 있어요 means “can go”, while 갈 수 없어요 means “cannot go”. 먹을 수 있어요 means “can eat”, while 먹을 수 없어요 means “cannot eat”.

This form can describe many kinds of inability: physical inability, lack of skill, schedule problems, rules, or outside circumstances. 오늘 갈 수 없어요 can mean “I cannot go today” because of time, plans, health, or another reason.

Compared with 못, which you will learn in the next point, -(으)ㄹ 수 없어요 sounds a little more explanatory and structured. It is very useful when you want to sound clear and polite.

못 is another very common way to say “cannot”. It is usually placed before the verb, like 못 가요, 못 먹어요, and 못 해요.

The feeling of 못 is often that something prevents the action: lack of ability, lack of time, bad condition, outside circumstances, or practical difficulty. 오늘 못 가요 means “I can’t go today.” 매운 음식 못 먹어요 means “I can’t eat spicy food.”

With 하다 verbs, 못 often comes before 해요: 운전 못 해요, 공부 못 해요, 수영 못 해요. This is very natural in daily speech.

The difference between 못 가요 and 갈 수 없어요 is subtle. 못 가요 is shorter and very conversational. 갈 수 없어요 is more structured and slightly more explanatory. Both are useful, but 못 is what you will hear constantly in real life.

잘 means “well”. It is used before verbs to say that someone does something well. 한국어를 잘해요 means “I speak Korean well.” 요리를 잘해요 means “I cook well.”

잘 못 means “not well” or “poorly”. Be careful: spacing and pronunciation matter. 잘 못해요 means “I cannot do it well / I am bad at it.” In daily speech, this often sounds like a soft way to say you are not good at something.

For example, 한국어를 잘 못해요 means “I don't speak Korean well.” This is extremely useful for learners. It is more natural and humble than saying only 한국어를 못 해요, which can sound like “I cannot speak Korean at all.”

You can also combine this with questions. 한국어 잘하세요? means “Do you speak Korean well?” To answer modestly, you can say 아직 잘 못해요, meaning “I still don't speak it well yet.”