"once I ran into her"
"once we are home, we can rest"
"at one time he loved her"
"her erstwhile writing"
"she was a dancer once"
1.一次；一回
If something happensonce, it happens one time only.
e.g. I met Wilmaonce, briefly...
我曾经和威尔玛有过短短的一面之缘。
e.g. Since that evening I haven'tonce slept through the night...
从那天晚上之后，我没有睡过一次安稳觉。
2.（与后接day, week, month等的a连用）（每…）一次，（每…）一回
You useonce with 'a' and words like 'day', 'week', and 'month' to indicate that something happens regularly, one time in each day, week, or month.
e.g. Lung cells die and are replaced aboutonce a week...
肺细胞约每周新老更替一次。
e.g. We arranged a special social eventonce a year to which we invited our major customers.
我们每年举办一次专门的社交活动，邀请重要客户出席。
3.（与后接day, week, year等的every连用）（每隔…）一次，（每隔…）一回
You useonce with 'every' and words like 'day', 'week', and 'year' to indicate that something happens a specified number of times and on a regular basis.
e.g. The patient was seen for follow-up visitsonce every three months...
这位病人每三个月接受一次随访就诊。
e.g. My daughter comes to visit meonce every fortnight.
我女儿每两周来看我一次。
4.曾经，一度（状况如此）
If something wasonce true, it was true at some time in the past, but is no longer true.
e.g. The culture ministeronce ran a theatre...
这位文化部长曾经经营过一家剧院。
e.g. I lived thereonce myself, before I got married...
我结婚前曾独自在那儿住过。
5.曾经（做过某事）
If someoneonce did something, they did it at some time in the past.
once的意思
e.g. Ionce went camping at Lake Darling with a friend...
我曾和一位朋友在达令湖畔露营。
e.g. Weonce walked across London at two in the morning...
我们曾在凌晨两点步行穿过伦敦。
6.一旦…（就…); 一…（就…）
If something happensonce another thing has happened, it happens immediately afterwards.
e.g. The decision had taken about 10 secondsonce he'd read a market research study...
在他看过一份市场调研报告后大概10秒钟就作出了决定。
e.g. once customers come to rely on these systems they almost never take their business elsewhere...
顾客一旦依赖上这些系统，几乎就不会光顾其他商家。
7.突然；忽然
If something happensall at once, it happens suddenly, often when you are not expecting it to happen.
e.g. I feel terribly sleepy all atonce...
我突然觉得特别困。
e.g. All atonce there was someone knocking on the door.
忽然有人敲门。
8.立即；马上
If you do somethingat once, you do it immediately.
e.g. I have to go, I really must, atonce...
我得走了，我真的必须马上就走。
e.g. Remove from the heat, add the parsley, toss and serve atonce...
端离炉子，加上欧芹，颠起翻面后就立刻上桌。
9.同时；一起
If a number of different things happenat once orall at once, they all happen at the same time.
e.g. You can't be doing two things atonce...
不能一心二用。
e.g. No bank could ever pay off its creditors if they all demanded their money atonce...
如果所有的储户同时要求提取存款，没有哪家银行能办得到。
10.就此一次；破例一次
For once is used to emphasize that something happens on this particular occasion, especially if it has never happened before, and may never happen again.
e.g. Foronce, dad is not complaining...
爸爸这次破天荒地没有抱怨。
e.g. His smile, foronce, was genuine.
只有这一次，他真诚地笑了。
11.又一次；再次
If something happensonce again oronce more, it happens again.
e.g. Amy picked up the hairbrush and smoothed her haironce more...
埃米拿起发梳，再次将头发梳理整齐。
e.g. once again an official inquiry has spoken of weak management and ill-trained workers.
官方调查又一次提到了管理不力与工人缺乏训练的问题。
12.彻底地；一劳永逸地
If something happensonce and for all, it happens completely or finally.
e.g. We have to resolve this matteronce and for all...
我们必须彻底解决这一问题。
e.g. If we act fast, we canonce and for all prevent wild animals in Britain from suffering terrible cruelty.
如果我们迅速采取行动，就可以一劳永逸地使英国的野生动物免受残忍的虐待。
13.偶尔；间或
If something happensonce in a while, it happens sometimes, but not very often.
e.g. Earrings need to be taken out and cleanedonce in a while.
耳环要偶尔取出来清洗一下。
e.g. once in a while she phoned him.
她间或会给他打个电话。
14.一两次；几次
If you have done somethingonce or twice, you have done it a few times, but not very often.
e.g. I popped my head round the dooronce or twice...
我有几次头撞到了门上。
e.g. once or twice she had caught a flash of interest in William's eyes...
有那么一两次，她发现威廉的眼睛里流露出一丝感兴趣的神色。
15.（常用于儿童故事的开头）从前，很久以前
once upon a time is used to indicate that something happened or existed a long time ago or in an imaginary world. It is often used at the beginning of children's stories.
e.g. 'once upon a time,' he began, 'there was a man who had everything.'...
“很久很久以前，”他开始说道，“有这么一个人，他应有尽有。”
e.g. once upon a time, asking a woman if she has a job was quite a straightforward question.
从前，问一位女性是否有工作是个相当简单直接的问题。
16. once in a blue moon -> see moon
1. 一次：最佳外语片的提名也没有<>,竞争这个奖项的有罗马尼亚电影,金棕榈奖获奖者<>、以色列电影<>(The Band''s Visit)、爱尔兰电影<>(once)和两部法国片,故事片<>(La
2. 曾经：<>(The Bourne Ultimatum)成為今年截至目前好評程度僅次於<>的全面公映作品,即便算上小範圍點映的愛爾蘭音樂劇情片<>(once)、伊拉克戰爭題材紀錄長片<>(No End in Sight),
3.once：open network computing environment; 网驰平台
4.once：online course engine; 在线课程引擎
