Expressing your abilities or the possibility of something is an important thing to know in any language. In Korean expressing your abilities or possibilities is done with the expression -(으)ㄹ 수 있다. To indicate something is beyond your abilities or something is impossible, you can use its negative -(으)ㄹ 수 없다. Let’s take a look.
-(으)ㄹ 수 있다
To express you are capable of doing something or something is possible to happen, is an important thing to know in any language. In Korean, you can use the expression -(으)ㄹ 수 있다 just for that. This Korean grammar pattern is the counterpart of the English modal verb ‘can’. And, in most instances, you can simply use it like you would in English.
가: 한국 드라마를 이해할 수 있어요?
나: 네, 드라마를 조금 이해할 수 있지만 뉴스는 정말 못해요.
A: Can you understand Korean dramas?
B: Yes, I can somewhat understand Korean dramas, but I really cannot understand the news.
-(으)ㄹ 수 없다
The Korean pattern -(으)ㄹ 수 없다 is the negative form of -(으)ㄹ 수 있다. Thus it expresses that you are incapable of doing something or that something is impossible. As you might guess, this opposite bears a striking resemblance with the negation form -지 못하다 and 못. That assumption would be correct and you can typically use one or the other. However, -(으)ㄹ 수 없다 has a stronger connotation to it than -지 못하다.
가: 내일 쇼핑할까요?
나: 내일 공휴일이라서 쇼핑할 수 없어요.
A: Shall we go shopping tomorrow?
B: We can’t go shopping because tomorrow is a public holiday.
How To Use
Using either -(으)ㄹ 수 있다 or -(으)ㄹ 수 없다 is very simple and you only need to keep a select few things in mind. The most important thing to keep in mind is that you can only use this pattern with verbs. You cannot use these with adjectives unless you’ve turned them into verbs with -아/어지다. The patterns themselves follow the ‘batchim/no batchim’ rule. This means you use -ㄹ 수 있다/없다 when the verb stem ends in a vowel and -을 수 있다/없다 when it doesn’t. Lastly, you can elect to add the subject particle -가 to the 수 of -(으)ㄹ 수 있다/없다. This adds greater emphasis on the fact something is either possible or impossible.