下面是小编整理的一些关于as、for和since的用法和区别， 希望对大家有帮助。

as和for都有“因为”的意思.但是as比for的语气弱.as用来表示显而易见的原因,而for却有一种解释说明的语气.

例：as it is raining,we have to call of the meeting.

please forgive him,for he is only 13 years old.

for ,because,as,since这四个词作为连词,都有"因为"的意思,但它们在用法上有区别：

because 是从属连词,接表示直接原因的从句,一般放在主句的后面,也可放在主句前面,它表示的语气最强,在回答why的问句时,必须用because.

例如：The swimming pool won't be open today because they're making repairs.

游泳池今天不开放,因为他们在修理.

Why did you move to France?

你们为什么搬到法国?

Because my father found work in Paris.

因为我父亲在巴黎找到了工作.

注意：在英语中用了because后,不可再用so.

as 是从属连词,说明一般的因果关系,语气比because弱,说明比较明显的原因,它引导的从句通常放在句首,有时也可放在句末.

例如：As it is raining, you'd better take a taxi.

天下雨了,你最好乘出租车.

since 意为"既然",表示对方已知的无需加以说明的原因或事实,语气比because弱,但是比as 强.

例如：Since we have no money, we can't buy that vase.

既然我们没钱,我们就不能买那花瓶.

Since everybody is here, let's begin our party.

既然大家都到了,那就开始我们的聚会吧!

for 是并列连词,用来附带解释说明前一分句的原因或理由,for引导的并列句,一般放在所要说明的句子的后面.

例如：I went to see him, for I had something to tell him.

我去见他,因为我有事要告诉他.