Cannot

The 수 있다 and 수 없다 forms to say that you can or cannot do something were already covered in a previous chapter.

저는 갈 수 있어요.

I can go.

저는 갈 수 없어요.

I can't go.

Saying can’t using 못 with an action verb

Put 못 before an action verb, with a space, to say that you cannot do the action. It can be used in the same sentences in which 안 can be used.

저는 못 가요.

I can't go.

저는 못 믿어요.

I can't believe it.

저는 기타를 못 쳐요.

I can't play the guitar.

저는 이해 못 했어요.

I could not understand.

Saying can't using 지 못하다

Just like 지 않다 can be used to make a verb negative, 지 못하다 can be used to say you can't with any verb.

1. Get the verb stem.
2. Attach 지 못하다.
3. Conjugate 지 못하다. For the regular present tense, this would be 지 못해요.

저는 가지 못해요.

I can't go.

저는 이해하지 못해요.

I can't understand.

저는 독일어를 하지 못해요.

I can't speak German.

여기서 바다를 보지 못하겠어요.

I won't be able to see the ocean from here.

Different 못 forms compared

If a verb is able to use either 못 or 지 못하다, just use either of them, they have the same meaning.

저는 매달 못 가요. / 저는 매달 가지 못해요.

I can't go every month.

Do not confuse these forms with the verb for saying you are bad at something, 못하다.

저는 노래를 잘 못해요.

I'm not good at singing.

As already covered in a previous chapter, you also have the 수 없다 form to say you don’t have the ability to do something. So use this if you specifically want to say that you don’t have the ability to do something, or that there’s no way for something to happen.
The opposite is 수 있다 which would mean you have the ability to do something.

Here is a comparison of the four:

Form	Example	Typical meaning
못 + action verb	수영를 못 해요	I can’t swim.
Verb stem + 지 못하다	수영하지 못해요	I can’t swim.
Activity noun + 못하다	수영을 못해요	I can’t swim / I’m bad at swimming.
Verb stem + 을/ㄹ 수 없다	수영할 수 없어요	I can’t swim.

As long as the sentence is grammatically correct the difference in nuance between 못 with an action verb, 지 못하다 and 수 없다 doesn’t matter too much.

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Sources & References

• Billy Go’s Beginner Korean Course | #81: Cannot