은 거 알다

you know that, right?

States a fact and checks that the listener knows it: 홍삼이 몸에 좋은 거 아시죠? "you know red ginseng is good for you, right?", 김치가 종류가 진짜 많은 거 알고 계신가요? "did you know there are so many kinds of kimchi?". Most of the 알다 lines here are that check — 알죠?, 아시죠?, 아실까요? — used by a presenter to bring the audience along before explaining something. Two other lines only look alike: 이거 당연한 거 너무 쉬운 거 아냐? is 아니다 "isn't it?", not 알다. The -ㄴ/-은 form points at a state or something already the case.

Register: explanatory; addressed to an audience