状语从句
状语从句在复合句中作状语，修饰动词、形容词或副词等。状语从句可以表示时间、条件、原因、地点、目的、结果、让步、方式、比较等意义。
各类状语从句连接词（短语）
时间 when, while, as, as soon as, since, until, after, before
条件 If, unless
原因 As, because, since
地点 Where
目的 So that, in order that
结果 So that, so…that, such…that
让步 though, although, even if, however
方式 As
比较 than, (not)as…as
时间状语从句：
Whenever he comes, he brings a friend. 他每次来都带个朋友。
条件状语从句：
As long as I am alive, I will go on studying. 只要我活着， 我就要学习。
原因状语从句：
Since we live near the sea, we enjoy nice weather.由于我们住在海边，能享受到好的天气。
地点状语从句：
Put it where we can all see it.把它放在我们都能看到的位置。
目的状语从句：
Finish this so that you can start another.把这个做完，你可以开始另一个。
结果状语从句：
He was so angry that he couldn’t say a word. 他气得说不出话了。
让步状语从句：
Though he is in poor health, he works hard.虽然他身体不好，但是他工作很努力。
方式状语从句：
Students do as the teachers say.学生们按照老师说的去做。
比较状语从句：
The work isn’t as easy as I thought.这项工作比我想象得难。
1.易混引导词while, when, as的区别：
when既可以指“时间点”,与瞬间动词连用，也可以指“时间段”，与延续性动词连用（=while）。如：
When he came in, his mother was cooking.
When (While) we were at school, we went to the library every day.
While表示时间段,因此，while 从句的谓语动词要用延续性动词。如：
Please don’t talk so loud while others are working.
As与when用法相似，但着重强调主句动作与从句动作同时发生，有“随着……”或“一边……一边……”之意。如：
As you get older, you get more knowledge.随着年龄的增长，你获得的知识就越多。
2．Because,as,since 的区别：
Because用于表示直接原因,回答why提出的问题，语气最强；As用于说明原因, 着重点在主句，常译成“由于”；since表示显然的或已知的理由或事实，常译成“既然”。如：
Water is very important because we can’t live without it.
He didn’t come yesterday as his mother was ill.
I’ll do it for you since you are busy.
3．such…that, so…that, so that 引导结果状语从句的区别：
such是形容词，修饰名词; so 是副词，修饰形容词或副词。其结构如下：
1) such + a (n)+ 形容词+单数可数名词+that……
2) such+形容词+复数可数名词+that ……
3) such +形容词+不可数名词+that……。如：
This was such a good film that I went to see it several times.
It was such good books that they sell well.
It was such bad weather that I had to stay at home.
He spoke so fast that I couldn’t follow him.
He is such a lovely boy that we all like him.
=He is so lovely a boy that we all like him.
注：在“形容词+可数名词复数/不可数名词”结构中，当名词前有many, much, few, little表示数量的多少时，名词前用so。
如：She made so many mistakes that she didn’t pass the exam.
