있었던 거야

was/were ...ing

→ 있다
phrase Rare #25,875
was/were ...ing Used after a verb, often as -고 있었던 거야, to explain or confirm what someone was doing. Depending on context, it can sound like “you were ...ing?” in a question.
KO: 그때 너를 기다리고 있었던 거야.
EN: I was waiting for you then.

그래서 지금껏 마시고 있었던 거 야?

So that's what you've been drinking all this time?

— 잠입자 (1979)