once
- adv.（每隔…）一次，（每隔…）一回;一次也，完全;（每…）一次，（每…）一回;一旦;曾经，一度;（用于否定句、疑问句和if后）曾，根本;<方>立刻;<古>将来总有一天;乘以一
- conj.一旦…（就…），一…（就…）;当…时候
- n.一次，一回
- adj.从前的，一度的
onceadv.
仅一次；一次
on one occasion only; one time
I've only been there once.
我只去过那里一次。
He cleans his car once a week.
他每周洗一次汽车。
She only sees her parents once every six months.
她每半年才探望一次父母。
He only did it the once .
这种事儿他仅仅干过一次。
曾；曾经
at some time in the past
I once met your mother.
我曾经见过你母亲。
He once lived in Zambia.
他曾在赞比亚生活过。
This book was famous once, but nobody reads it today.
这本书曾名噪一时，但现在却无人问津。
（用于否定句、疑问句和if后）曾，根本
used in negative sentences and questions, and after if to mean ‘ever’ or ‘at all’
He never once offered to help.
他从没有主动提出过帮忙。
If she once decides to do something, you won't change her mind.
她一旦决定干什么，谁也改变不了她的主意。
on this occasion (which is in contrast to what happens usually)
只有这一次他按时到了。
Just for once he arrived on time.
Can't you be nice to each other just this once?
难道你们就不能彼此客气哪怕一次？
one more time; another time
火车又一次晚点了。
Once again the train was late.
Let me hear it just once more.
让我再听一遍。
used to say that sb cannot change
一朝从艺，永为艺人。
Once an actor, always an actor.
now and for the last time; finally or completely
我们需要把这事一次解决。
We need to settle this once and for all.
after an unpleasant experience you are careful to avoid sth similar
very rarely
occasionally
a few times
我跟她不很熟；我只见过她一两次。
I don't know her well, I've only met her once or twice.
used to say that sb has done sth wrong or stupid again, and this time they will suffer because of it
你故技重施，可这次再逃不脱了。
You've tried that trick once too often.
used, especially at the beginning of stories, to mean ‘a long time in the past’
从前，有一位美丽的公主。
Once upon a time there was a beautiful princess.
conj.
一…就；一旦；当…时候
as soon as; when
We didn't know how we would cope once the money had gone.
一旦钱花光了，我们就不知道该怎么办了。
The water is fine once you're in!
你一旦下了水，就会觉得水里挺舒适。
once
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1
ADV 一次；一回
If something happens once, it happens one time only.I met Wilma once, briefly...
我曾经和威尔玛有过短短的一面之缘。
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2
ADV （与后接day, week, month等的a连用）（每…）一次，（每…）一回
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.Lung cells die and are replaced about once a week...
肺细胞约每周新老更替一次。
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3
ADV （与后接day, week, year等的every连用）（每隔…）一次，（每隔…）一回
You use once with 'every' and words like 'day', 'week', and 'year' to indicate that something happens a specified number of times and on a regular basis.The patient was seen for follow-up visits once every three months...
这位病人每三个月接受一次随访就诊。
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4
ADV 曾经，一度（状况如此）
If something was once true, it was true at some time in the past, but is no longer true.The culture minister once ran a theatre...
这位文化部长曾经经营过一家剧院。
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5
ADV 曾经（做过某事）
If someone once did something, they did it at some time in the past.I once went camping at Lake Darling with a friend...
我曾和一位朋友在达令湖畔露营。
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6
CONJ-SUBORD 一旦…（就…); 一…（就…）
If something happens once another thing has happened, it happens immediately afterwards.The decision had taken about 10 seconds once 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。
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7
PHRASE 突然；忽然
If something happens all at once, it happens suddenly, often when you are not expecting it to happen.I feel terribly sleepy all at once...
我突然觉得特别困。
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8
PHRASE 立即；马上
If you do something at once, you do it immediately.I have to go, I really must, at once...
我得走了，我真的必须马上就走。
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9
PHRASE 同时；一起
If a number of different things happen at once or all at once, they all happen at the same time.You can't be doing two things at once...
不能一心二用。
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10
PHRASE 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.For once, dad is not complaining...
爸爸这次破天荒地没有抱怨。
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11
PHRASE 又一次；再次
If something happens once again or once more, it happens again.Amy picked up the hairbrush and smoothed her hair once more...
埃米拿起发梳，再次将头发梳理整齐。
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12
PHRASE 彻底地；一劳永逸地
If something happens once and for all, it happens completely or finally.We have to resolve this matter once and for all...
我们必须彻底解决这一问题。
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13
PHRASE 偶尔；间或
If something happens once in a while, it happens sometimes, but not very often.Earrings need to be taken out and cleaned once in a while.
耳环要偶尔取出来清洗一下。
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14
PHRASE 一两次；几次
If you have done something once or twice, you have done it a few times, but not very often.I popped my head round the door once or twice...
我有几次头撞到了门上。
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15
PHRASE （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.'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。”
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16
once in a blue moon→ see:moon
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You 'll like her once you get to know her .
你一旦了解了她就会喜欢她的。
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The water is fine once you 're in !
你一旦下了水，就会觉得水里挺舒适。
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I need to have it out with her once and for all .
我有必要跟她公开彻底地把话说清楚。
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The industry today is nothing to what it once was .
这一行业的现状与昔日的盛况相比微不足道。
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She 's planning to return to work once the children start school .
她正计划孩子一入学就恢复上班。
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I 'll run back over the procedure once again .
我将重新考虑这个程序。
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It 's a lot of information to absorb all at once .
要一下子消化这么多资料，真是很难。
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If necessary I can come at once .
如果有必要，我可以马上来。
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A computer can perform many tasks at once .
电脑能同时做多项工作。
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Since the party she had only spoken to him once .
那次聚会以后，她只和他说过一次话。
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If I 've said it once , I 've said it a hundred times .
这事我曾经说过，而且是说过很多次了。
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An opportunity like this comes once in a lifetime .
像这样的机会一生也许只会遇到一次。
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It made a refreshing change to be taken seriously for once .
总算有一次受到认真对待，这变化真是令人耳目一新。
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He was once the great white hope of British boxing .
他一度曾是英国拳击的希望所在。
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We need to settle this once and for all .
我们需要把这事一次解决。
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She only sees her parents once every six months .
她每半年才探望一次父母。
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We go there maybe once or twice a month .
我们每月大概去那里一到两次。
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' Come here at once ! ' she ordered .
“马上过来！”她命令道。
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We didn 't know how we would cope once the money had gone .
一旦钱花光了，我们就不知道该怎么办了。
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She fell in with my idea at once .
她立刻同意了我的主意。
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Traditional stories make use of formulaic expressions like ‘ Once upon a time …’ .
传统故事采用“从前…”一类的套语。
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If you can only exercise once a week , that 's better than nothing .
即便是一个星期锻炼一次，也比完全不锻炼好。
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It was once thought that the sun travelled around the earth .
人们曾经认为太阳绕着地球转。
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Let me hear it just once more .
让我再听一遍。
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Once again , the train was late .
火车又晚点了。
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There once was a poor farmer who had four sons .
从前有一个贫苦的农夫，他有四个儿子。
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We have several projects all on the boil at once .
我们热火朝天地同时上马了几个项目。
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It was once thought that lead could be transmuted into gold .
有人曾经认为铅可以变成黄金。
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I don 't know her well , I 've only met her once or twice .
我跟她不很熟；我只见过她一两次。
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It is a physical impossibility to be in two places at once .
同时身处两地在自然法则上是不可能的。
- 习语
同义词