임을

that ... is

→ 이다

phrase Rare #22,129

that ... is A formal written construction formed from 이다 and the object particle 을. It nominalizes a statement, often after a noun, as in “realizing that it is a mistake.”

KO: 그 결정이 최선임을 믿어요.

EN: I believe that decision is the best option.

하지만 출발 전날 잘못된 결정 임을 깨달았어요

But I realized the day before departure that it was the wrong decision.

— 콘클라베 (2024)