状语从句是在句子中做状语的从句，由从属连词引导，主要分为八大项：
1、时间状语从句、 2、地点状语从句、
3、目的状语从句、 4、结果状语从句、
5、原因状语从句、 6、条件状语从句、
7、让步状语从句、 8、比较状语从句。
1、时间状语从句，引导词＂when、while、as、until(till)、not until、since、ever since、each time、whenever、once、the moment、as soon as、no sooner...than、scarcely/hardly...before/when＂
eg: when I reached the booking office,all the tickets had been sold.
while there is life there is hope.
Bill sang as he worked.
I will stay at my office until(till) it stops snowing.
Until you told me I had no idea of what mary said.
Not until the teacher came did we begin the experiment.
He has been riding since he was six.
Each time I meet him,I talk seriously to him.
She said she would phone me the moment she reached there .
once you begin to learn korean,you will find it interesting.
no sooner had the picnic baskets been unpacked than it began to rain.
Scarcely had the lights been turned off when he fell asleep.
2、地点状语从句，引导词" where 、wherever ”
eg : A driver should slow down where there are many houses.
He wanted to go wherever he could find work.
3、目的状语从句，引导词"so that、 in order that 、lest 、for fear that 、in case"
eg: The chairman hurried the meeting so that/in order that it might end before dark.
The President must reject this proposal lest it should cause violence.
Shut the window for fear that it may rain.
Take you umbrella in case it rains.
4、结果状语从句，引导词"so that 、so/such...that、 such that 、that "
eg: Our camp is so far from the highway that we feel apart from the world when we are there.
He made such a marvelous speech that he won warm applause.
His answer was such that he didn't say yes and he didn't say no.
5、原因状语从句，引导词"because、as、since、now that、seeing that、considering that、in that"
eg: I teach because I enjoy finding ways of getting myself and my students out of the ivory tower and into the real world.
As women were not supposed to be novelists,the writer took the name George Eliot.
Since no one is against it,we will adopt the proposal.
Now that you are all here,let's try to discuss the problem.
Mary has done very well considering she has only one year experience of teaching.
I like the city,but I like the country better in that I have more friends here.
6、条件状语从句，引导词"if、unless、so/as long as 、provided that、providing that、on condition that、suppose that、supposing that、when、in case"
eg:Supposing we can't get the necessary funds,what shall we do?
You can camp in my field provided that you leave no mess.
7、让步状语从句，引导词"though、although、 even though(even if)、as 、while、疑问词 +ever (no matter+疑问词结构)"
eg：Though Jimmy was very tired,he kept on working.
He insisted on doing it although I wanted him not to.
John said he would;he didn't ,although.
Even though I become a millionaire, I shall always be thrifty with my money.
Difficult as the experiment was,it was well done by them.
While I admit his good points,I can see his shortcomings.
You will have the same result,whichever(no matter which) way you do it.
Come and see me,whenever(no matter when) you are in Paris.
8、比较状语从句，引导词"as...as、 not so/as...as 、more/-er...than"
eg：She is as tall as Tom.
She is not as/so tall as Tom is.
She behaves more politely than him.
The house is much taller than it is wide.
