Unit 23: Can and Cannot (-(으)ㄹ 수 있어요 / 없어요)

Do you remember how we made the future tense in Unit 21 by adding -(으)ㄹ followed by 거예요? We use that exact same building block to say "I can" or "I cannot"!

Instead of 거예요, we add 수 있어요 (can) or 수 없어요 (cannot). (Note: "수" roughly translates to "way" or "ability".)

1. How to conjugate

The rules for adding -(으)ㄹ are identical to the future tense rules.

Rule 1: Vowel stem -> + ㄹ 수 있어요 / 없어요

• 가다 (to go) -> 갈 수 있어요 (I can go).
• 하다 (to do) -> 할 수 없어요 (I cannot do it).

Rule 2: Consonant stem -> + 을 수 있어요 / 없어요

• 먹다 (to eat) -> 먹을 수 있어요 (I can eat).
• 읽다 (to read) -> 읽을 수 없어요 (I cannot read).

Rule 3: ㄹ stem -> + 수 있어요 / 없어요 (Do not add anything!)

• 놀다 (to play) -> 놀 수 있어요 (I can play).
• 만들다 (to make) -> 만들 수 없어요 (I cannot make it).

2. Examples in Context

Scenario 1: A: 오늘 만날 수 있어요? = Can we meet today? (만나다 = to meet) B: 아니요, 바빠요. 만날 수 없어요. = No, I am busy. I cannot meet.

Scenario 2: A: 한국어 할 수 있어요? = Can you speak (do) Korean? B: 네, 할 수 있어요. = Yes, I can do it.

3. Alternative to "Cannot": 못

Instead of using the long form -(으)ㄹ 수 없어요, Koreans very often use the short adverb 못 (mot) placed directly in front of the verb. It functions exactly like 안 (Unit 18), but means "cannot" instead of "do not".

• 먹을 수 없어요 = 못 먹어요 (I cannot eat).
• 갈 수 없어요 = 못 가요 (I cannot go).

Note: For 하다 verbs, just like with 안, you split the noun and the verb: 수영 못 해요 (I cannot swim).

Summary

• Vowel: ㄹ 수 있어요 (Can) / ㄹ 수 없어요 (Cannot)
• Consonant: 을 수 있어요 (Can) / 을 수 없어요 (Cannot)
• Short form for Cannot: Place 못 before the verb.