1、原因状语从句原因状语从句一、一、because,since和和as引导的原因状语从句引导的原因状语从句because，since，as这三个词都可引导原因状语从句。Because表示直接的原因或理由直接的原因或理由，着重点在从句，用于回答why，语气最强，常译为“因为”。Since一般表示对方已知的、无须加以说明的既成事实的理既成事实的理由由，全句中心在主句，语气比because弱，常译为“既然”。As表示十分明显的原因十分明显的原因，一般说明因果关系，着重点在主句，语气较弱，常译为“由于”。Difference 1.The doctor told the patient to go on a
2、 diet he was overweight.A.on the condition of B.because C.for D.when2.the weather was fine,I opened all the windows.A.As B.Because of C.For D.With3.you are leaving tomorrow,we can eat dinner together tonight.A.For B.Since C.Before D.WhileABB在强调句式强调句式中，若强调原因壮语从句，只能用because引导的从句。Example:It was because
3、 he was ill that he didnt go with us.正因为他病了，他才没和我们一起去。二、二、for 和和 because，as，since的区别的区别4.The fuel must have been finished,the engine stopped.A.since B.as C.because D.forbecause，as，since总是表示因果关系，而且语气较强；而for引导的是并列分句，它只是对前面的分句加以解释，说明推断的理由，并且只能后置只能后置。We did not go out because it was raining.（因为下雨，我们没有出去
4、It must have rained last night,for the ground is wet this morning.（昨晚一定下雨了，因为今天早上地都是湿的。）D三、短语连接词引导的原因状语从句三、短语连接词引导的原因状语从句5.that my head had cleared,my brain was also beginning to work much better.A.For B.Now C.Since D.Despite I havent finished writing the report yet,Im lazy,I have no time.我还没有写完报告
5、不是因为我懒，而是因为没有时间。Translate a sentence:Bnot that but that四、某些介词词组引导的原因状语从句四、某些介词词组引导的原因状语从句6.He was not severely punished for his crime that he was young.A.on the ground B.in the case of C.in view of D.on conditionby reasonfor fearfor the reasonon the groundA.because，since，as这三个词都可引导原因状语从句。其中because语气较强语气较强，主要用以回答由why引出的问句，since次之次之，as最弱最弱。since和as表示的原因多是既成事实。若从句表示的原因还不是确定的事实，就不能用since。Summary:.在原因状语从句中，for引导的从句并不说明主句行为发生的直接原因，只是提供一些补充说明，且不可位于主句前不可位于主句前。.除了一般的连接词外，还可用短语连接词&某些介词词组如by reason等来引导原因状语从句。
