줄 (jul) · 수 (su)
'줄' mainly expresses intention or promise, while '수' indicates possibility or means.
One lane per word — no nested boxes, just the gist.
Used to express someone's intention, promise, or an action done for someone else.
When to use
Expressing intention, Expressing promise, Action for someone else
The nuance
Attached to verb stems as '-ㄹ/을 줄 알다/모르다/생각하다' to express intention, expectation, or promise.
Used to express possibility, method, or means.
When to use
Expressing possibility, Expressing method/means, Inevitable situation
The nuance
Attached as '-(으)ㄹ 수 있다/없다' to indicate possibility, and '-는 수밖에 없다' to indicate method or necessity.
나는 그가 올 줄 몰랐다.
na-neun geu-ga ol jul mol-rass-da., na neun geu ga ol jul mol rass da.
'줄' is used when talking about intention or expectation.
나는 그가 올 수 몰랐다.
na-neun geu-ga ol su mol-rass-da., na neun geu ga ol su mol rass da.
'수' expresses possibility, but with '모르다' '줄' is correct.
내가 도와줄 줄 알았어?
nae-ga do-wa-jul jul al-ass-eo?, nae ga do wa jul jul al ass eo?
'줄' is used to ask about someone's intention or promise.
내가 도와수 있을까?
nae-ga do-wa-su iss-eul-kka?, nae ga do wa su iss eul kka?
'도와수' is ungrammatical; correct form is '도와줄 수'.
이 문제를 해결할 수 있다.
i mun-je-reul hae-gyeol-hal su iss-da., i mun je reul hae gyeol hal su iss da.
'수' is used to express possibility.
이 문제를 해결할 줄 있다.
i mun-je-reul hae-gyeol-hal jul iss-da., i mun je reul hae gyeol hal jul iss da.
'줄' is for intention or promise; '수' should be used for possibility.
그는 나를 도와줄 줄이다.
geu-neun na-reul do-wa-jul jul-i-da., geu neun na reul do wa jul jul i da.
'줄이다' is a different word and ungrammatical here.
그는 나를 도와줄 수 있다.
geu-neun na-reul do-wa-jul su iss-da., geu neun na reul do wa jul su iss da.
'수' is used to express ability or possibility.
Which is used to express intention or promise, '줄' or '수'?
Which sentence correctly uses '수'?
What role does '줄' play in '도와줄 줄 알았어?'
