before的用法 before是什么意思


before的用法 before是什么意思

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一、It be some time +before…
此句型关键有四种含义,分别阐述如下:
1.该句中主句为将来时态,before从句为一般现在时态;主句为一般过去时,从句通常也为过去的时态 。
2.例如:
It will be some months before we graduate from school.(过几个月,我们就毕业了 。)
Shall we see him again? (我们还能见到他吗?)
I think so. It won’t be long before he comes back to the hometown.(我想会的,过不了多久他又返回家乡 。)
该句型中的时间长为long, a long time, years, months, weeks, days, hours, minutes等时间段 。此句型容易与强调句型混淆,试比较:
It was two years before he came back from abroad.(过了两年他才从国外回来 。)
It was two years later before he came back from abroad.(两年之后他才从国外回来 。)
第一句为状语从句,it 表示时间;第二句为强调句型,强调的是时间状语two years later 。
3.该句型的引申为“还没来得及……就……” 。请看例句
Someone called me up in the middle of the night, but they hung up before I could answer the phone.(半夜里有人打电话,但是我还没来得及回答他就挂了 。)
before的用法 before是什么意思

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4.该句型还有一个引申含义为“……之后才……”,多与持续性时间、动作连用 。例如:
Several weeks had gone by before I realized the painting was missing.(几周之后,我才意识到那幅画丢了 。
二、“not…before”句型有时可换成“hardly…when…”或“scarcely…when”句型
例如:
They had not talked for half an hour before she entered. =They had hardly/scarcely talked for half an hour when she entered.
三、“not…before”句型同“not…until”句型意思相同,表示“直到……才,在……以前不……”(即在否定句中,until 和 till 可以和非延续性动词连用,这时 until 和 before 近义)
比较例句:
She stood there till/until he had passed out of sight.(不用before)他一直站在那儿,直到他消失 。
The moon will not come out until/before the clouds disappear.云散了月亮才会出来 。
One doesn’t know the value of health before/until he loses it.人们失去了健康后才知道健康的珍贵 。
四、Before, after与behind
before表时间、顺序或排列时与after相对;表位置时与behind相对 。例如:
I saw the headmaster the day before yesterday.我前天见到了校长(时间) 。
Autumn comes before winter.秋去冬来(顺序) 。
A comes before B in the alphabet.在字母表里A排在B之前(排列) 。
五、before long与long before
before long是“很快,不久(以后)”的意思,等于soon,可以用于各种时态,例如:
Before long he got married.不久他就结婚了 。
before的用法 before是什么意思

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而long before是“很久以前”的意思,等于long long ago,一般用在过去时或过去完成时的句子里 。例如:
I saw the film long before.我很久以前就看过这部电影 。
另外,before在不同的语境中会产生不同的含义,学生、教师在学习、教学中要认真研究,加以甄别 。例如:
Linda has grown into a beautiful girl before she knows it.不知不觉Linda已长成一个亭亭玉立的少女 。
Do it before you forget.趁早动手,免得忘记 。
Be a pupil before you become a teacher.先做学生再做老师 。
Lucy desired no one for her husband before Charles Darnay.
Lucy非Charles Darnay不嫁 。
I’ll shoot myself before I apologize to him.我宁死也不向他道歉 。
The ship sailed before the wind.轮船顺风而行 。
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