1. all at once(=all of a sudden): 갑자기 예문: All at once, the lights went out in the house(갑자기 집 안의 불이 꺼졌다.) 같은 뜻의 단어: Suddenly, Abruptly, Unexpectedly, Out of the blue, Without warning 2. at once: 곧, 즉시에(immediately, right now) When the fire alarm rang, everyone evacuated the building at once.( 화재 경보가 울리자마자 모두 건물을 대피했다.) ↓ ●at one’s+최상급: 한창~한 She was at her happiest when she was traveling around t..