英语总结（二）——原因状语从句

原因状语从句

用法

在句中用来说明主句原因的从句。

连接词

because, as, since, now that, seeing that, considering that

简单例句

He likes me because I'm smart.他喜欢我，因为我聪明。
Since (=now that)you're here,you can help me.既然你在这儿，你可以帮我。

要点

because

引导原因状语从句表达一种充分理由，因果关系明显，语气较重，可回答why引导的问句。
不可以与 so 连用。

- 例句
We went by bus because it was cheaper.

since

引导原因状语从句指已知的很显然的原因，语气比because弱，较为正式，不能用来回答why引导的问句。

- 例句
Since you are here, you can help me.

as

表示双方都知道的原因，语气比since弱，较为正式。

- 例句
As you are tired, you had better rest.
As we all know, he has died.

for

引导的并列分句，它只对前面的主句加以解释，补充说明，并且只能后置，前面用逗号与主句隔开。

- 例句
He seldom goes out now, for he is very old.