before的用法總結(jié)(2)
before的用法總結(jié)
二、掌握熱點(diǎn)句型用法
It was not long before...(過去)沒過多久就......
It was not long before he returned to Beijing. 不久他就回到北京。
需要特別注意，該句型可以進(jìn)行創(chuàng)新，可將否定句改為肯定句(It was long before...過了很久才......)或?qū)⒁话氵^去時(shí)改為一般將來時(shí)(It will not be long before...要不了多久就......;It will be long before...要過很久才......)。before在這些句型中均引導(dǎo)時(shí)間狀語從句， long這個(gè)抽象的時(shí)間也可改為years, weeks, days等具體表時(shí)間的詞。
It was long before he married Wei Fang. 過了很久他才娶魏芳。
It will be long before he goes abroad. 要過很久他才出國(guó)。
Will it be years before he goes to school? 要過好幾年他才能上學(xué)嗎?
高考題例：
It ________ long before we ________ the result of the experiment.
A. will not be...will know B. is...will know C. will not be...know D. is...know
【析】正確答案為C。該句面意思為：在我們知道實(shí)驗(yàn)結(jié)果之前不會(huì)過很長(zhǎng)一段時(shí)間，也就是不會(huì)過很長(zhǎng)一段時(shí)間我們就會(huì)知道實(shí)驗(yàn)結(jié)果。應(yīng)使用It was not long before的創(chuàng)新句型It will not be long before，before引導(dǎo)時(shí)間狀語從句時(shí)，從句應(yīng)用一般現(xiàn)在時(shí)代替一般將來時(shí)。
Scientists say it may be five or six years ________ it is possible to test this medicine on human patients.
A. since B. after C. before D. when
【析】正確答案為C。該句型也是It was not long before的創(chuàng)新句型。
when與befor的區(qū)別
本文結(jié)合典型例題來歸納一下before的特殊用法。
before作為連詞時(shí)的基本意義是“在……之前”，用于表示時(shí)間或順序。如：Turn the light off before you sleep. (睡前先把燈熄掉。) Think before you speak. (說話之前，應(yīng)先想清楚。) 但在不同的語境中before有不同的意義：
1. before表示“不等……就……”、“尚未……就……”
例1： —Why didn’t you tell him about the meeting? (2006年四川)
—He rushed out of the room I could say a word.
A. before B. until C. when D. after
解析： 答案為A。題中before意為“不等……就”、“尚未……就……”，它表示從句的動(dòng)作尚未來得及發(fā)生，主句的動(dòng)作已發(fā)生或完成。全句句意為：我還沒來得及說他就沖出了房間。又如：
Before I could get in a word, he had measured me. 我還沒有來得及插上話，他就給我量好了尺寸。
The phone stopped ringing before I answered it. 我還沒有來得及接，電話就掛了。
2. before表示“不知不覺，還沒弄清就……”(常用于before sb. know/realize…)
例2： Several weeks had gone by I realized the painting was missing. (2004全國(guó))
A. as B. before C. since D. when
解析： 此題最易錯(cuò)選C或D項(xiàng)，而正確答案為B。用since則時(shí)間延續(xù)到了現(xiàn)在，在時(shí)間上與had gone矛盾;用when則無法強(qiáng)調(diào)時(shí)間流逝的不知不覺性。又如：
Time passed quickly and three months went by before I knew it. 時(shí)間飛快地流逝，不知不覺3個(gè)月過去了。
3. before表示“以免，不然”
例3： It’s cloudy. Take an umbrella you regret it.
A. but B. and C. after D. before
解析： and及but表示并列關(guān)系，不合語境;after意為“在……之后”，不合常識(shí)，應(yīng)是在下雨前帶傘;before在此處意為“以免你后悔”。before作此意義的用法的例子不少，又如：
Put that away before it gets broken. 把它收好，以免砸了。
Do it before you forget. 盡早動(dòng)手，不然忘了。
4. before用于it was / will be + 時(shí)間 + before ... 句型中。
例4： It won’t be long you regret what you have done.
A. after B. before C. since D. until
解析： It was / will be + 時(shí)間 + before ... 表示“過了多久才…(強(qiáng)調(diào)時(shí)間的長(zhǎng))”，在否定句中則表示“沒過多久就…(強(qiáng)調(diào)時(shí)間的短)”。例如：
It will be two years before we meet again.我們要過兩年才能見面。
It wasn’t long before he married again. 不久他就又結(jié)婚了。
We didn’t wait long before he came back. 我們沒等多久他就回來了。
5. before表示“與其……寧可……，比……優(yōu)先”(用于表優(yōu)先順序)
例5： They would fight to death they surrendered(投降).
A. before B. after C. since D. because
解析： 答案為A。before引導(dǎo)的從句在與will, would連用時(shí)，有“寧愿……也不”的含義。before即使是作介詞用也有此意義。例如：
True men choose death before dishonor. 大丈夫?qū)幙蓺⒉豢扇琛?/p>
I’d die before I apologize to them! 我寧死也不愿向他們道歉!
We will die before we give in. 我們寧死不屈。
6. before表示“……才”(強(qiáng)調(diào)從句動(dòng)作發(fā)生得晚或慢)
例6： They sailed along the Pacific Ocean for two weeks they arrived home.
A. since B. when C. before D. after
解析： 此題正確答案為C。全句句意為：“他們?cè)谔窖蠛叫辛藘蓚€(gè)星期才回到家。”強(qiáng)調(diào)從句動(dòng)作比主句動(dòng)作發(fā)生晚。又如：
I thought carefully about it before I made a decision. 我經(jīng)過再三考慮才決定。
It may be many years before the situation improves. 或許要過很多年這種狀況才能得到改善。
下面有一道2003年的高考題：
Don’t be afraid of asking for help ____ it is needed.
A. unless B. since C. although D. when
本題答案為D，考查when作連詞的用法。此處when相當(dāng)于if，意為“如果，要是”。
下面我們來歸納一下when 的用法：
1.作疑問副詞，意為“什么時(shí)候，什么場(chǎng)合”。如：
I don’t know when he died.
我不知道他何時(shí)去世的。
Since when has he been missing?
他是從什么時(shí)候失蹤的?
2.作關(guān)系副詞，引導(dǎo)定語從句。如：
He came at a time when we needed help.
他在我們需要幫助的時(shí)候來了。
We’ll never forget the day when we joined the Party.
我們永遠(yuǎn)不會(huì)忘記我們?nèi)朦h的那一天。
3.作連詞，引導(dǎo)時(shí)間狀語從句。如：
?、俦硎?ldquo;當(dāng)……的時(shí)候”、“無論什么時(shí)候”、“一……的時(shí)候”之意。如：
It was raining when we arrived.
我們到的時(shí)候天正在下雨。
When I was a boy, I used to go to the Western Hills on Sundays.
小時(shí)候，我經(jīng)常在星期天到西山公園去玩。
It is cold when (whenever) it snows.
一下雪天就冷。
He joined the PLA when (as soon as) he returned home.
他回家后就參了軍。
?、谝鉃?ldquo;可是，然而，既然，考慮到”。如：
How can they learn anything when they spend all their spare time watching television?
他們把所有的空閑時(shí)間都用來看電視了，還能學(xué)什么東西呢?
They have only three copies when we need five.
他們只有三本，可我們需要五本。
The waitress brought me coffee when I asked for tea.
雖然我叫了茶，女服務(wù)員卻拿了咖啡給我。
?、?意為“如果，要是”。如：
You shall have the apple when you say “Please”.
你要是說“請(qǐng)”，這蘋果就是你的。
He will likely recover when he undergoes the operation.
如果動(dòng)手術(shù)的話，他可能會(huì)復(fù)元。