because, as, since, fo表示原因状语时的区别

 

      [作者：未知  整理: DoWell 2007-1-27 ]

 

      because, as, since, for都可以用来表示“因为”。它们之间的区别只是一些细微的区别，要完全把它们分别出来是不容易的，因为它们主要只在“语气”轻重上有区别。另外，就是在句子所处的位置有些差别。希望大家通过阅读例句，体会这种区别。

 

      1、because
      because引导原因状语从句语气最强，表示直接原因,常用来回答由why提出的问题，所引导从句可放在主句前，也可放在主句后。例如：
      Well, many people travel because they want to see other countries.
      He is absent because he is ill.
      Because he didn't catch the last bus, he had to walk home.
      Why are you late for school ? Because I missed the first bus.
      The swimming pool won't be open today because they're making repairs.
      Why did you move to France? Because my father found work in Paris.
      [注]because 可以用于否定句中，其它词则不行。例如：
      I did it not because I liked to do it but because I had to do it.

 

      2、as
      as引导原因状语从句，语气比because弱，说明比较明显的原因,多用于日常语中，常译为“由于”，从句一般放于主句前。例如：
      As he wasn't ready in time, we went without him.

      As he is ill, he won’t go.
      I must stop writing now, as I have rather a lot of work to do.
      As you don't feel well,you had better stay at home.
      As it is raining, you'd better take a taxi.

 

      3、since
      since引导原因状语从句，语气比because弱，但是比as 强。强调说话者和听者双方都知道的原因，常译为“既然”，一般用在这样的句子里。例如：
      Since you are not feeling well, you may stay at home.
      Since everybody is here, let's begin the meeting.
      Since I am a boy, let me carry the case.
      Since/As you are busy, you had better not go with us.
      Since we have no money, we can't buy that vase.
      [注] now that也有此意。如：
      Now that you have finished your work, let’s go now.

 

      4、for
      for是用来附带解释或说明前一分句的原因和理由，有时它表示的理由是推测性的。for引导的从句一般放在主句后，用逗号和主句分开。例如：
      I had to stop for a rest, for I was too tired.
      Day breaks, for the cock crows.
      It must have rained last night, for the ground is wet.
      I won't go in, for my father is there.
      He diden't wanted to go out,for he was unhappy.
      He paid me less than the others, for I'm female.
      I went to see him, for I had something to tell him.

 

      [注]比较下列句子：
      He is absent, because he is ill.（“生病”是“缺席”的必然原因。)
      He is absent, for he is busy. (“忙”不是必然原因，只是一种解释。）
      He must be ill, for he is absent. (for表示对原因的一种猜测。)