1. because 标明直接缘由，它所指的缘由一般是听话人所不晓得的，口气最强。常用来答复why的发问，一

般放于主句之后，也可以单独存在。

He was absent from school because he was ill.

他没去上学，因为他病了。

2. since 偏重主句，从句标明显着的或已为人所知的理由，常译为“因为”、“已然”，口气比because稍弱，一般置于句首，标明一种富含牵强口气的缘由。

Since everyone makes mistakes, you shouldn’t always criticize him.

已然每自个都会犯差错，你不大约老是批判他。

3. as 比照口语化，标明比照显着的缘由或是已知实际，所引导的从句常放在主句之前。从句阐明缘由，主句阐明成果，主从偏重。

As it is raining hard, let’s do something indoors.

雨下得很大，咱们就做点室内活动吧。

4. for 不标明直接缘由，只标明附加或揣度的理由，前后两个分句间的逻辑联络不必定是因果联络，其间用逗号离隔，且for不可以置于句首。

The day brakes, for the birds are singing.

天亮了，鸟儿在叫。

5. seeing that，considering that 和 now that 引导的缘由状语从句。

He is in the marriage bureau business, which is mildly ironic seeing that

his dearest wish is to get married himself.

他从事婚姻介绍作业，这多稀有点讥讽意味，因为他最大的期望就是自个能成婚。

Considering that you are no longer involved with this man, your response is a little extreme.

思考到你现已与这自个划清了鸿沟，你的反应有一点儿过头。

Now that you are well again, you can travel.

已然你身体好了，你如今可以旅行了。