|
一、 原因状语从句
在句中用来说明主句原因的句子叫作原因状语从句。通常由because, since, as，for引导。
（1）because表示直接原因，语气最强。Because引导的原因状语从句多放在主句之后。回答由why提出的问题，只能用because。
------Why aren’t going there? ------Because I don’t want to.
I did it because he told me to.
（2）Since和now that语气比because弱，常翻译为“既然”一般用来表示明显的原因。由since引导的原因状语从句多放在句首。
Since we have no money, we can’t buy it.
Now that you are busy, let me do it for you.
（3）as语气比since弱，表示附带说明的 双方已知的原因，含有对比说明的意味。
As he has no car, he can’t get there easily.
（4）for引导的，不说明主句行为发生的直接原因，只提供一些辅助性的补充说明，并且只能放于主句之后.
We must start early tomorrow, for we have a long way to go.
It must be morning for the birds are singing.
二、目的状语从句
用来补充说明主句中谓语动词发生的目的的状语从句。
(1)目的状语从句通常由 so that, in order that（为了，以便）引导。例如：
We started early so that we could catch the first train.
We used the computer in order that we might save time.
(2) 目的状语从句的谓语常含有may ,might , can , could , should , would 等情态动词
三、 结果状语从句
在句中用来作结果状语的句子叫结果状语从句。
经常由so…that, such…that, 引导。
（1）在由so...that引导的结果状语从句中，so是副词，与形容词连用。
... so + 形容词（副词）+ that…
..so + 形容词+ a/an + 可数名词单数+that...
He was so glad that he couldn’t say a word.
It was so hot a day that we all went swimming.
(2)由such…that引导的结果状语从句中，such是形容词
such+a/an +形容词+可数名词单数+ that
such+形容词+可数名词复数/不可数名词+ that
It was such a hot day that nobody wanted to do anything.
He had such long arms that he could almost touch the ceiling.（天花板）
有时上述两种结构是可以互换的。例如：
It is such an important match that nobody wants to miss it.=The match is so important that nobody wants to miss it.
(3)如果名词前由many, much, little, few等词修饰时，只能用so, 不用such。例如：
Soon there were so many deer that they ate up all the wild roses.
He has so little time that he can’t go to the cinema（去看电影） with you.
|
