英 [wʌns] 美 [wʌns]
adv. 一次， 一回；曾经，一度；任何一次，从来；乘以一
conj. 一.....就， 一旦
n. 一次
once /wʌns/ CET4 TEM4
副词 If something happens once, it happens one time only. 一次
I met Miquela once, briefly.
我见过蜜凯拉一次，时间很短。
Since that evening I haven't once slept through the night.
自那晚之后，我再也没睡过一次囫囵觉。
代词 Once is also a pronoun. 一次
"Have they been to visit you yet?"—"Just the once, yeah."
“他们已经去看过你了吗？”— “来过，就那一次。”
副词 You use once with "a" and words like "day," "week," and "month" to indicate that something happens regularly, one time in each day, week, or month. 每隔…一次
Lung cells die and are replaced about once a week.
肺细胞约每周死亡、更新一次。
副词 If something was once true, it was true at some time in the past, but is no longer true. 从前
Her parents once ran a shop.
她父母从前开过一家商店。
I lived there once myself, before I got married.
我从前自己住在那儿，没结婚前。
副词 If someone once did something, they did it at some time in the past. 曾经
I once went camping at Lake Michigan with a friend.
我曾和一个朋友去密执安湖野营。
We once walked across the frozen pond at two in the morning.
我们曾在凌晨2点徒步横穿冰冻的池塘。
连词 If something happens once another thing has happened, it happens immediately afterward. 一…就
The decision had taken about 10 seconds once he'd read a market research study.
他读完一份市场调研报告后，10秒钟就做出了决定。
习语 If something happens all at once, it happens suddenly, often when you are not expecting it to happen. 突然
All at once there was someone knocking on the door.
突然有人敲门。
习语 If you do something at once, you do it immediately. 立刻
I have to go at once.
我得马上走。
Remove from the heat, add the parsley, toss and serve at once.
从火上端下来，加入香芹，搅拌后立刻上桌。
习语 If a number of different things happen at once or all at once, they all happen at the same time. 同时
You can't be doing two things at once.
你不能同时做两件事。
习语 For once is used to emphasize that something happens on this particular occasion, that it has never happened before, and may never happen again. 就此一次
For once, Dad is not complaining.
就这一次，爸爸没有抱怨。
习语 If something happens once again or once more, it happens again. 再一次
Amy picked up the hairbrush and brushed her hair once more.
艾米拿起梳子，又梳了一遍头发。
习语 If something happens once and for all, it happens completely or finally. 最终地
We have to resolve this matter once and for all.
我们必须彻底解决这件事情。
习语 If something happens once in a while, it happens sometimes, but not very often. 偶尔
Your body, like any other machine, needs a full service once in a while.
你的身体就像其他机器一样，偶尔也需要一次全面保养。
习语 If you have done something once or twice, you have done it a few times, but not very often. 一两次; 几次
I visited once or twice.
我参观过一两次。
Once or twice she had caught a flash of interest in William's eyes.
有一两次，她捕捉到威廉眼中一闪的关注。
as soon as
once we are home, we can rest
一次
不过正如娜姐决赛中的对手斯齐亚沃尼一样，她也曾经(Once)是在2010年法网前名不见经传，但2010年法网一鸣惊人夺冠，命好不如习惯好。养成好习惯，一辈子受用不尽。
... Games),在两个最严重的典礼上易胜博最新备用网址都呈现过熄火(Extinction)情景,一次易胜博最新备用网址忽然有意扑灭,一次(Once)是由于微风气象?绕鹨馔庀ɑ穑?
... 8.(每一) each; per; every time (一旦; 一经) once; as soon as 剂量,(一)剂,(一): dose ...
...其实我最喜欢开头那句Once Doesn't mean anything to me，和结尾的那声叹气，无奈的感觉［人生最大的痛苦莫过于此］． Once 过去 Doesn't mean anything to me 留给我虚幻的回忆 ..
I met Miquela once, briefly.
我见过蜜凯拉一次，时间很短。
For once, Dad is not complaining.
就这一次，爸爸没有抱怨。
I've only been there once.
我只去过那里一次。
But,once the fire is out, the well still needs to be covered,or capped, to stop the flow of oil.
VOA : special.2009.03.22
Then, once you've done that, once you have secured the integrity and accuracy of the meaning, Hirsch says, "Okay, fine.
在你完成那个之后，一旦你确定了意思的真实性和准确性，赫施说，好的，不错。
文学理论导论课程节选 : 耶鲁公开课
And once you... when you're having that bad of a season, it's really hard to get everyone passionate about it,
所以一旦赛季取得很差的成绩，就很难保持球队的激情，
SpeakingMax英语口语达人 : 足球部队长的领导力
This year,on July fourth, visitors once again will be able to climb inside the statue all the way to the top.
VOA : special.2009.06.29
There is literally concrete evidence of their work." Tony Hawk says skateboarding was once a sport on the edge of society.
VOA : special.2009.09.11
Her brush with death made her decide once and for all: The weight had to go.
The once unstoppable green machine lost its mojo at the Climate Change Conference in Copenhagen.
One can see that this was once a vibrant city with an active commercial class.
"once"是个多义词，它可以指曾经,once（戴安娜·威克斯演唱歌曲）,once（原田瞳演唱歌曲）,once（校园恋爱游戏）,once（陈珊妮、阮经天演唱歌曲）,once（英语单词）,once（方大同演唱歌曲）,once（电影《曾经》原声大碟）。