"因为"的用法

because:因为.强调直接原因. (接从句) because of后接短语
since:因为.强调双方已知无需用说明的事由. 后接从句,表间接原因
for:因为.强调一种推测.但不一定是事实. (接名词性短语,表主观原因)
as:强调一般因果关系.用于句首.(后接名词)

Because she's ill,she can't go to my home.因为她病了,所以她没有来我家.
注:because后接句子,而because of后接短语.
Since everyboby is here,let's begin our meeting.
既然大家都到了,那就开始开会吧.
Day breaks,for the birds are singing.
因为鸟儿在唱歌了,天可能亮了.
As he was not well,i decided to go without him.
由于他身体不太好,我决定不带他去.
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because, as, for, since这几个词都是表示“原因”的连词，语气由强至弱依次为：because→since→as→for;其中because, since, as均为从属连词，引导原因状语从句；而for 是并列连词，引导并列句。

1. because表示直接原因，它所指的原因通常是听话人所不知道的，其语气最强。常用来回答why的提问，一般放于主句之后，也可以单独存在。例如：

(1)I stayed at home because it rained. 因为下雨我呆在家里。

(2)Because Lingling was ill, she didn't come to school. 玲玲因病，没有上学。

(3)—Why is she absent? 她为什么缺席？

—Because she is sick. 因为她病了。

此外