状语从句一．分类：
时间状语从句：
when (当……的时候) while (在……期间) as (当……的时候, 一边……一边……)
before (在……之前) since (自从……以来)
till/until (直到) hardly…when… (刚……就)
as soon as (一……就……) after (在……之后) not…till/until（直到……才）no sooner…than…(刚……就)
地点状语从句： where (在那里) wherever(无论哪里)
原因状语从句：because (因为) since (因为，既然) as (由于) for (为了) now that（既然）
目的状语从句：（so）that=in order that（以便） so as（not）to （以便[不]） in case（以免） lest（以免）
结果状语从句：so+adj./adv.+that（如此……以致） so that（结果……）
such+n.+that（如果……以致）
that（所以，因此）
让步状语从句：though/although不可同but连用。

though/although （虽然） however （可是） even though/if（即使）
no matter+what/which/where/who/when
=whatever/whichever/wherever/whoever/whenever
（不论什么/哪一个/哪里/谁/何时）
比较状语从句：as （正如）as…as（和……一样） not as/so … as （不如……） than（比……更）
the+比较级…+the+比较级（越……越……）条件状语从句：if（假设） unless（如果不） so long as （只要） on condition that （如果）
方式状语从句：as（像……那样地） just as（正像） as if（好像） as though（好像）
二．各种状语从句的简化方法：
1．以after和before引导的状语从句的主语若与主句主语一致时，从句等于after/before+doing sth.作状语。

例：After she sang，she left the rich man's house． = After singing，she left the rich man's house．
2．以as soon as引导的状语从句的主语若与主句主语一致时，从句等于on+doing sth.,作状语，此时的动词为非延续性动词。

例：Mary began to operate on the wounded soldiers as soon as he arrived at the village．
= Mary began to operate on the wounded soldiers on arriving at the village．
3．时间状语从句和条件状语从句的主语和主句主语一致时，有时可简化为不定式作状语。

例：She stopped when she saw her husband． = She stopped to see her husband．
If you want to understand the farmers，you must go to the countryside．
= To understand the farmers，you must go to the countryside．
4．结果状语从句和目的状语从句的主语与主句主语一致时，可以简化为不定式作状语；若两者主语不一致时，则应简化为不定式的复合结构作状语。

例：He was so tired that he couldn't go any further．= He was too tired to go any further．
I came here so that I could ask some questions．= I
came here(in order) to ask some questions．
5．以when，while引导的时间状语从句和以if引导的条件状语从句的主语若与主句主语一致时，从句等于when/while/if +doing sth.作状语，表示谓语动作发生在该状语动作的进行过程之中。

例：When he turned on the radio，he found it broken．= When turning on the radio，he found it broken．
While she was walking along the street，she was hit by
a car．= While walking along the street，she was hit by
a car．
6．原因状语从句的主语与主句主语一致时，可简化为分词短语作状语。

例：Since l didn't know Chinese，I tried to speak to her in English．= Not knowing Chinese，I tried to speak to her in English．
注意：形容词短语也可作表示原因的状语，来代替原因状语从句，放在句首、句末均可，但一般应加逗号。

例：As he was thirsty and eager to get a little rest，he went into the tea-house．
= Thirsty and eager to get a little rest，he went into the tea-house．
7．在时间、原因、条件等状语从句中，若从句和主句主语不一致时，可简化为分词复合结构作状语。

有时也可简化为“with/without名词或代词十分词(短语)”形式作状语。

例：When the film start appeared, the children got exited．= The film start appearing，the children got exited．
If all the work is done, you can have a rest．= With all the work done，you can have a rest．
Nothing can live if there is no air．= Nothing can live without air．
8．让步状语从句的主语与主句主语一致时，可简化为分词短语作状语；不一致时，常简化为with或in spite of介词短语
作状语。

例：Although he faced his death，he didn't say anything before the enemy．
= Facing the death，he didn't say anything before the enemy. Although there was danger，he rushed out to carry the boy to safety．
= In spite of danger，he rushed out to carry the boy to safety．
三．表示"一…就…"的结构
hardly/scarcely…when/before, no sooner…than 和as soon as都可以表示"一…就…"的意思，例：I had hardly / scarcely got home when it began to rain.
I had no sooner got home than it began to rain.
As soon as I got home, it began to rain.
注意：如果hardly, scarcely 或no sooner置于句首，句子必须用倒装结构：
Hardly / Scarcely had I got home when it began to rain.
No sooner had I got home than it began to rain.
四．As引导的让步状语从句的倒装：
1．形容词+as+主语+系动词：
例：Tired as he is, he offers to help me. 尽管他已经很累了，他还是主动提出帮助我。

2．过去分词+as+主语+系动词：
例：Well-known as the book is, the author is not satisfied and prepared to revise it.
尽管这本书写得很好,作者还是不满意并打算修改它。

3．名词+as+主语+系动词：
例：Student as he is, he does not study hard. 他虽然是个学生，但却不努力学习。

4．副词+as+主语+谓语部分：
例：Much as I admire his courage, I don’t think he acted wisely.
我虽然钦佩他的勇气，但我认为他这样做是不明智的。

5．动词原形+as+主语+谓语的剩余部分：
例：Try as you will，you won’t be able to persuade him. 不管你怎么努力，你都说服不了他。