Overview
The grammar pattern (으)ㄹ 수 있다/없다 is a fundamental expression in Korean used to convey ability, capability, or possibility. It allows speakers to state whether an action can be performed or if a situation can occur. The choice between 있다 (to exist, to be) and 없다 (not to exist, not to be) determines whether the statement is affirmative (can/possible) or negative (cannot/impossible).
Usage
This pattern is attached to the stem of a verb to express two main ideas:
- Physical or Mental Ability: It indicates that the subject has the skill, strength, or knowledge to perform a particular action. For example, "I can speak Korean" (한국어를 할 수 있어요).
- Situational Possibility: It signifies whether a certain event or action is feasible or permissible given the circumstances. For example, "It's too noisy, so I can't study" (너무 시끄러워서 공부할 수 없어요).
The pattern is versatile and widely used in everyday conversation to discuss what is within one's reach or what circumstances allow.
Conjugation Rules
The conjugation depends on the final sound of the verb stem:
- Verb stem ending in a vowel or the consonant ㄹ: Add -ㄹ 수 있다/없다.
- 가다 (to go) -> 갈 수 있다/없다
- 만들다 (to make) -> 만들 수 있다/없다 (Note: The ㄹ is retained)
- Verb stem ending in a consonant (other than ㄹ): Add -을 수 있다/없다.
- 먹다 (to eat) -> 먹을 수 있다/없다
- 읽다 (to read) -> 읽을 수 있다/없다
Knowledge Plus
- Distinction from -지 못하다: While (으)ㄹ 수 없다 also means "cannot," -지 못하다 often implies a lack of skill or an external obstacle preventing an action, sometimes with a nuance of regret or failure. (으)ㄹ 수 없다 is more neutral, simply stating the impossibility. For example, "저는 수영을 못 해요" (I can't swim - lack of skill) vs. "지금은 수영을 할 수 없어요" (I can't swim right now - perhaps due to time or location).
- Dependent Noun '수': The '수' in this pattern is a dependent noun meaning "way," "method," or "possibility." It is always preceded by a modifying clause (the verb stem + (으)ㄹ) and followed by 있다/없다. This is why there's a space between (으)ㄹ and 수.
- Formal vs. Informal: This pattern is widely used in both formal and informal contexts. The formality changes with the ending of 있다/없다 (e.g., 있어요/없어요, 있습니다/없습니다).