英语中since和before的用法?

英语中since和before的用法?
英语中since和before的用法?

英语中since和before的用法?
一、可以用作介词
⒈)指时间上早于,在……之前,如：
She has lived here since before the war.
她从战前就一直在这儿住.
⒉)指位置在前面,如：
We knelt down before Grandma‘s grave.
我们在奶奶的墓前跪下.
⒊)指顺序或排列在之前,如：
Your name comes before mine on the list.
名单上你的名字在我之前.
⒋)在某人面前,如：
She said it before the witness.
他是当着证人的面说的.
二、作为连词
其基本含义是“在……之前”,又可以根据不同语境灵活翻译成“才”、“还没来得及就……”、“趁……”、“就”等.具体用法如下：
⒈)与情态动词can/could连用
这时候从句虽为肯定形式,根据汉语表达习惯译成“还没来得及就”,如：
Before I could get in a word,he had measured me.
我还没来得及插话他就为我量好了尺寸.
Before she could move,she heard a loud noise,which grew to a terribl eroar.
她还没来得及迈步,就听见一声巨响,接着就是可怕的隆隆轰鸣.
⒉)用于肯定句中强调主句所表达的时间,距离长,或花费的精力大,译成“才”
We had sailed four days and four nights before we saw lands.
我们航行了四天四夜才看到陆地.
We waited a long time before the train arrived.
我们等了很长时间火车才到.
⒊)用于否定句中,强调主句所表达的时间,距离短,或花费的精力小,译成“不到……就”如：
We hadn‘t run a mile before he felt tired.
我们跑了还不到一英里他就累了.
⒋)主句含有hardly,scarcely等半否定副词时可以译为“刚……就”
这时候主句应用过去完成时态,从句用过去时,还可以用when替代before如：
We had scarcely reached the school before/when the bell rang.
我们刚到学校铃声就响了.
⒌)有时还有“宁愿”的意思
I‘d shoot myself before I apologized to him.我宁死也不向他道歉.
⒍)用于It+be/take+时间段+before句型
在这一句型中又可以根据主从句的时态分成两种情况.
若主句是一般时将来时态,从句是一般现在时.若主句是肯定句意思是“要过多长时间才”；若主句是否定形式翻译成“用不了多久就”.
It will be two weeks before everything returns to normal.
两周之后一切才能恢复正常.
It will be many years before the situation improves.
这种状况或许要过许多年才能得以改善.
It won‘t be long before we meet again.用不了多久我们就会再见面的.
这时若主句是一般过去时从句也是一般过去时.若主句是肯定句翻译成“多长时间之后才”,若主句是否定形式翻译成“没过多久就”.如：
It was some time before I realized the truth.
过了很长一段时间我才了解到真相.
It wasn‘t long before she became a brave solider.
没过多久她就成了一名勇敢的战士.
After that it still took seven years before they got married.
他们又过了七年才结婚.
注意：当主句的谓语动词为延续性动词时,before与until有时可以互换.It was an hour before/until the police arrived.
■巩固练习
⒈(2004天津)It was evening ________ we reached the little town of Winchester.
Athat B.until C.since D.before
2.(2004全国)Several weeks had gone by ________ realized the painting was missing.
A.as B.before C.since D.when
3.(2005广东)The America Civil War lasted four years ______ the North won in the end.
A.after B.before C.when D.then
4.(2005山东)It was some time _______ we realized the truth.
A.when B.until C.since D.before
5.(2006四川)-Why didn‘t you tell him about the meeting?
-He rushed out of the classroom _______ I could say a word.
A.before B.until C.when D.after
6.(2006福建)-How long do you think it will be __ china sends a manned spaceship to the moon?
-Perhaps two or three years.
Awhen B.until C.that D.before
参考答案：DBBDAD

since多用在完成时中，表示“自……以来”；before多用在过去式中。在……之前。

since的意思是"自从"也可以翻译成"自....以来".
I have known him since 1990.从1990年我就认识他了.
She has worked hard since leaving school.
还可译为"既然"的意思.
Since everybody is here ,let's begin.既然大家都到了,那我们就开始吧....

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since的意思是"自从"也可以翻译成"自....以来".
I have known him since 1990.从1990年我就认识他了.
She has worked hard since leaving school.
还可译为"既然"的意思.
Since everybody is here ,let's begin.既然大家都到了,那我们就开始吧.
before:
1.(时间)在.....以前
We finished the work before noon.中午以前我们完成了工作.
2.(位置)在.....前面,当着.....的面.
He made a speech before a large audience.他在许多听众面前发表演说.
3.(顺序)在.....之前,先于.
Think it over before you qct. 行动之前你得仔细考虑一下.
4.(选择)宁可,宁愿.
I would die before surrendering to them.我宁愿死也不向他们投降.赞同3| 评论

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since表示自从，加点时间。
eg：He started playing basketball since he was five.
他自从5岁的时候开始打篮球
before是在.....之前

since1.主要接表示过去时间的短语或句子，“自。。。以来”
2.既然（表示原因）
before+时间点：在。。。之前
这两个在意思上就可以区别了