since 和before 作“以前”解释时的用法和区别?

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。before2。(2004全国)Several weeks had gone by ________ realized the painting was missing。A。as B。before C。since D。when3。(2005广东)The America Civil War lasted four years ______ the North won in the end。A。after B。before C。when D。then4。(2005山东)It was some time _______ we realized the truth。A。when B。until C。since D。before5。(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。after6。(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