all at once

without warning; suddenly

突然

all at once the noise stopped.

突然，吵鬧聲停止了。

all at the same time

同時

a lot of beans are ready all at once.

同時很多豆子準備好了。

for once (或this once)

on this occasion only, as an exception

就（這）一次；破例一回

I hope you'll forgive me this once.

我希望你就原諒我這一次。

once a ——, always a ——

(proverb)a person cannot change their fundamental nature

(諺)一次…始終…

once a whinger, always a whinger.

曾經是把短刀，始終是把短刀。

once again (或more)

one more time

又一次，再一次

once and for all (或once for all)

now and for the last time; finally

一勞永逸；徹底地

once and future

denoting someone or something that is eternal, enduring, or constant

永久的；持久的；持續(xù)的

side two contains four once and future hit singles.

第二面有四首持續(xù)走紅的單曲。

once bitten, twice shy

side two contains four once and future hit singles.

第二面有四首持續(xù)走紅的單曲。

once (或every once) in a while

from time to time; occasionally

偶然；間或

once or twice

a few times

一兩次

once upon a time

at some time in the past (used as a conventional opening of a story)

從前（用于故事的開頭）

at once

All at one time; simultaneously

立刻；同時

Everything happened at once. The view of the skyline is at once awesome, grand, and disappointing.

所有的事都一起發(fā)生了。天邊立刻呈現出令人敬畏的、壯麗的和令人沮喪的景色

Immediately; instantly

立即；馬上

Leave the room at once.

馬上離開這個房間