once/wʌns/

ad.

➊ one time

➋ in the past

conj. as soon as

ad.

➊ 一次：“Have you been to Beijing?” “Yes, but only once.” “你去过北京吗?” “去过，但只去过一次。”

◇He goes to the cinema once a week. 他一个星期去看一次电影。

➋ 曾，曾经：She once visited the ancient town. 她曾经参观过这个古镇。

conj. 一旦，一…（就…）：Once your decision is made, tell me. 你一做了决定，就告诉我。

once more (或again) 又一次，再一次：He did the exercise once more. 他把这个练习又做了一遍。

once upon a time 从前：Once upon a time, there was a beautiful and kind-hearted princess. 从前，有个美丽善良的公主。

构词源自one

辨析ever; once