before 英 [bɪ'fɔː(r)] 美 [bɪ'fɔːr]
conj. 在 ... 以前
pref. 在 ... 以前；在..前面
adv. 以前；以往；之前
介词
1、在…以前
before lunch
午餐前
the day before yesterday
前天
He arrived before me.
他比我先到。
Something ought to have been done before now.
先前就该采取措施了。
We'll know before long (= soon) .
我们很快就会知道了。
It happened before long. 不久就发生了。
It happened long before. 很久以前就已发生了。
注意：long before
很久以前 very long ago
We've seen that film film long before.我们早就看过那部电影了。
2、在…面前（或前面）（与behind相对）
They knelt before the throne.
他们跪在御座前。
Before you is a list of the points we have to discuss.
放在你面前的是一份我们要讨论的要点清单。
3、（次序或排列）在前面
Your name is before mine on the list.
名单上你的名字在我之前。
He puts his work before everything.
他一切以工作为重。
4、（表示面临或临近）
The task before us is a daunting one.
我们面临的任务令人胆怯。
The whole summer lay before me.
整个夏季正等待着我。
5、当面
He was brought before the judge.
他被带上法庭。
She said it before witnesses.
她当着证人的面讲出这事。
They had the advantage of playing before their home crowd.
他们有在主场观众面前比赛的优势。
6、（表示面对某人、某事时的反应）
They retreated before the enemy.
面对敌人，他们撤退了。
连词
1. 表示“在…..之前就…..”。
Mary had finished her homework before her mother returned.
玛丽在妈妈回来之前就完成了作业。
Do it before you forget.
尽早动手，免得忘了。
Did she leave a message before she went?
她走之前留言了吗？
2. 表示“过了多久后才…….. ，动作进行到什么程度才……”
The man almost knocked me down before he saw me .
那人差点把我撞倒了才看见我。
They walked about 30 miles to the west before they saw a village .
他们向西走了大约30英里才看见一个村庄。
They worked day and night about three days before everything returned to normal .
他们日夜工作大约三天后才一切恢复正常。
3. 表示“来不及； 尚未…..就…”
Before I could get in a word , he had measured me .
我还没来得及插话，他已经给我量好了尺寸。
He ran off before I could stop him .
我还没来得及阻止他，他就跑掉了。
She left the company before I could have a word with her .
我还没来得及跟她说句话，她就离开了公司。
4. 表示“刚…就…”before还可用于barely〔scarcely〕...before结构，意为“刚…就…”
hardly…when(before)…”和“scarcely…when(before)…”这两个结构在含义上与as soon as及no sooner…than相近,都作“一……就……”解。hardly(scarcely)引出主句,when(before)引出从句,主句的动作与从句的动作一前一后紧接着发生。有人主张主句的谓语动词要用过去完成时,从句用一般过去时。
"hardly…When(before)…”和“Scarcely…when(before)…”这两个结构在含义上与as soon as及no Sooner…than相近,都作“一……就……”解。hardly(scarcely)引出主句,when(before)引出从句,主句的动作与从句的动作一前一后紧接着发生。有人主张主句的谓语动词要用过去完成
I had barely come in before the telephone rang.我刚进来,电话就响了。
Barely had she sat down before the play began.她刚坐下,戏就开始了。
We had scarcely left the house,before it began to rain.我们刚刚离家，天就下起雨来。
Scarcely has a foreigner set foot in the United States before they ask him what he thinks of the country. 外国人刚去美国，他们就会问他对该国有什么看法。
Scarcely had they settled themselves in their seats in the theatre the curtain went up.
他们几乎没坐在剧院的座位上，窗帘就竖起来了。
I had hardly sat down before the bell rang.我一坐下来铃声就响了。
5. 表示“不知不觉就…..； 还没弄清就……”
Time passed quickly and three months went by before Aqiao knew it.
时间过得很快，等Aqiao意识时间的时候不知不觉三个月过去了。
6. 表示“宁愿…，决不…，与其…，毋宁….”常与will 或would 连用。
（宁可…而）不愿
相当于rather than
I'd die before I apologized!
我宁愿死也不道歉！
I would die before I would tell
我宁愿死也不愿告诉别人
I’d shoot myself before I apologized to him.
我宁愿开枪自杀也不会向他道歉。
I would / will die before I surrender .
我宁愿死也不投降。
He'd sit alone in the dark before he'd watch TV.他宁愿一个人在黑暗里坐着也不看电视。
We must stop and rest before going any farther.我们必须停下来休息一下再向前走。
7. 表示“否则；以免”
Do it now before you forget . 现在就行动吧免得忘记了。
I will write it down before I forget it .我马上下来以免忘记了。
Put that away before it gets broken.
把它收好，免得砸碎了。
8. 用于句型“it was 时间段 before …” 表示 “过了多久才…”相当于until
It may be many years before the situation improves.
这种状况或许要过很多年才能得到改善。
It was some time before I realized the truth.
过了很长一段时间我才悟出真相。
It was three days before he came back. .
before, till, until这三个词均可表示“在…之前”“直到”。
1).在否定句中, before和till或until可以互换,但前者强调句中动作在其宾语所指时间之前的进展情况,而后者则强调句中动作在其宾语所指时间之后的转变情况。
2).在肯定句中, before强调句中动作在其宾语所指时间之前已经完成或强调句中状态在其宾语所指时间之前持续的情况,因而句中可以用持续性动词或瞬间动词; till和until则强调句中动词所表示状态在其宾语所指时间之后的结束或转变情况。
9. 用于句型 “ it was not long 时间段 before …” 意为“不久就….”
It was not long before he sensed the danger of the position .
不久他就意识到了这个职位的危险。
It will be not long before you find you are wrong .
过不了多久你就会发现你错了。
10. 用于句型“it will be(not ) 时间段 before….”表示“要过多久/ 不久…才…”
It will be half a year before you graduate from this school .
要过半年你才能从这所学校毕业。
副词 以前；以往；过去
I've been here before...
我以前来过这儿。
11. 词汇搭配
动词 ～
appear before 在(某时)之前出现;出庭
carry before 迅速获胜,势如破竹
come before 在…之上,比…重要;被交由…处理；被提交…考虑
complain before 控诉
go before 出现在某人面前；送于…讨论；先于；早于
lay before 提出
set before 把…放在…前面；认为…比…更重要；把…提交…考虑
stand before 站立在…前面，来到…面前，面对，面临，抵御，抵挡
carry the world before one 一举大获成功
cast pearls before swine 对牛弹琴,明珠暗投
put the cart before the horse 本末倒置,倒行逆施
sweep all before one 获得彻底的胜利，所向无敌
be brought before the bench 被带到法庭受审
take sb before court 将…送上法庭
～ 名词
before day 破晓前
before long 不久,很快;在短时间内
before one's eyes 当着某人的面
before one's time 在时代前面;思想过于先进
before the mast 充当水手
before time 提前
before the wind 顺风
before the world 在众人面前，公然
the day before yesterday前天
the week before last 上上星期
～ 副词
before now 从前,以前
正误解析
铃还没响，同学们就走出去了。
［误］ The students went out before the bell didn't ring.
［正］ The students went out before the bell rang.
［析］ before引导的时间状语从句不能用于否定句。
知识拓展
before和ago都能表示在一段时间以前，但是二者的内涵和具体用法有明显的区别：
1. before表示从过去或将来某一时间算起多少时间以前，由于与这一时间状语连用的行为先发生在过去或将来某一时刻之前，因此往往出现在过去完成时态或将来完成时态中。例如：
① I called him up last night， but his mother told me he had left for Wuhan two days before.
② She said that she had married him five years before.
2.如果不具体表明多少时间以前，before意为“从前；以前”，表示从现在开始追溯到过去一段时间，或者主句的谓语动词表示的是经常、反复发生的行为，以副词的形式置于句末，可以用在现在完成时态中。例如：
①I have never been to Beijing before.
②Have you ever seen a tiger before?
③ I often go over the lessons that I have learned a few days before.
注意： before前的时间状语如果是特定的，含义不一样。试比较：
He said he had arrived here a day before. (一天前)
He said he had arrived here the day before. (前一天)
3. ago指的是从现在起到过去时间的某一点的一段时间。这个时间状语常与一般过去时态或过去进行时态连用。例如：
① I graduated from the college twenty years ago.
②I was asked what I was doing a month ago.
4. 表示在某一时间点或事件以前时，只能用before，不用ago。因为这种用法是将before当作介词或连词使用。ago不具有这种功能。例如：
① He will come back before eleven o'clock.
② Where did your brother study before he joined the army?
③ It was hoped that this would be achieved before the year 2006.
5.按语法规则，ago只能与一般过去时连用，但在since three years ago这类短语中能与现在完成时态连用。因为three years ago构成一个名词短语，共同作since的宾格，意为“自从三年前以来”。例如：
① He has been here since three years ago.自从三年前以来他一直在这儿。
② I have taught English in this school since twenty years ago.自从20年前以来我一直在这个学校教英语。
6. 含before的从句一般不用将来时态，如果采用“will / would V.”时，一般被认为是情态或虚拟语气。例如：
I would die before I would confess to it.
7.如果before从句是一般过去时态，所暗示的是过去发生的事，主句则宜用过去完成时，语义偏重于过去某阶段的行为或状况时，还可与一般过去时态连用。例如：
① I had never seen a Red Army man before I arrived in Xi'an.
② They asked me things that happened before the boy was born.
8. 不少的语法书上说，before引导的从句习惯上不与否定的主句连用，要用until。实际上二者都可以，有时在意义上有些区别。试比较：
He didn't arrive until I returned. 直到我回来时他才到达。
He did not arrive before I returned. 在我回来之前他尚未到达。
I didn't manage to do it until you had explained how. 直到你解释了如何干，我才设法完成了那项工作。
I didn't manage to do it before you had explained how. 你解释了如何干之后，我才设法完成了那件工作。
9. before在句中的含义比较灵活，虽然before引导的也是一个时间状语，但译成汉语时却不必死译为“在……以前”。可以采取下面几种译法：
（A）译为“……才”；
（B）译为“……就”；
（C）译为“尚未”、“还没有”、“来不及”、“不要”、“别”；
（D）译为“在……的时候还没有”；
（E）译为“如果”、“否则”、“免得”；（F）译为“到”、“等到”、“没等……就”；
（G）译为“然后”等。例如：
A. It will be five years before we meet again. 要等五年我们才能再见面。
We waited a long time before the train arrived. 我们等了很长时间火车才到达。
B. I hadn't waited long before he came. 我没等多久他就来了。
He had not gone a mile before he felt tired. 还没走一英里路，他就觉得累了。
C. His father died before he was born. 他尚未出世他父亲就去世了。
Catch him before he escapes. 抓住他，别让他跑了。
Take this computer before you change your mind. 买了这台电脑，不要三心二意了。
D. We arrived there before it began to rain. 我们到达那里的时候还没下雨。
E. Go before I call the police. 走吧，否则我叫警察了。
I had better go now before it is too late. 我最好现在就走，免得太迟。
Pigs will fly before he'll be a scientist. 如果他当科学家，猪都会飞了。
F. The crops will die before the rain fall. 等到天下雨，庄稼早枯死了。
Before I could sit down, he offered me a cup of tea. 没等我坐下，他就给我端上一杯茶。
G. I shaved before I went to the party. 我刮了脸，然后去参加宴会。
