-잖아요
you know (as you are aware)
Level 3 · Sentence ending
Explanation
Reminds the listener of something they already know, to explain or gently reproach. Attaches to the stem; past -았/었잖아요, nouns (이)잖아요. Conversational; avoid in formal speech to superiors.
Examples
제가 어제 말했잖아요.
I told you yesterday, remember?
오늘은 일요일이잖아요. 은행이 문을 안 열어요.
It's Sunday, you know. The bank is closed.
밖이 춥잖아요. 따뜻하게 입고 가요.
It's cold out, so dress warmly.
TOPIK note
TOPIK II Listening 4–20.