걸 알아차렸다

noticed that

→ 것+을

phrase Rare #16,497

noticed that 걸 is a shortened form of 것을, marking the preceding clause as the thing that was noticed. Depending on context, 알아차렸다 can also mean “realized.”

KO: 그가 긴장한 걸 알아차렸다.

EN: I noticed that he was nervous.