状语从句 （Adverbial Clause）
状语从句指句子用作状语时，起副词作用的句子。它可以修饰谓语、非谓语动词、定语、状语或整个句子。根据其作用可分为时间、地点、原因、条件、目的、结果、让步、方式和比较等从句。状语从句一般由连词(从属连词)引导，也可以由词组引起。从句位于句首或句中时通常用逗号与主句隔开，位于句尾时可以不用逗号隔开。
状语从句的种类：
用来修饰谓语动词、其它动词、定语、状语或整个句子的从句叫做状语从句。状语从句可分为：
1.时间状语从句；(adverbial clause of time)
2.地点状语从句；(adverbial clause of place)
3.原因状语从句；(adverbial clause of cause)
4.条件状语从句；(adverbial clause of condition)
5.目的状语从句；(adverbial clause of purpose)
6.让步状语从句；(adverbial clause of concession)
7.比较状语从句；(adverbial clause of comparison)
8.程度状语从句；(adverbial clause of degree)
9.方式状语从句；(adverbial clause of manner)
10.结果状语从句。(adverbial clause of result)
状语从句的时态特点：
一般情况下，时间和条件状语从句的谓语动词一般用“一般现在时”表示“一般将来时”，用“现在完成时”表示“将来完成时”。例如：
I will call you as soon as I arrive in Beijing. 我一到北京就给你打电话。（这是由as soon as引导的时间状语从句，从句中的谓语动词arrive是一般现在时，表示一般将来时，决不可用will arrive）
As soon as I have finished this work, I will go home. 我一完成此工作，就回家。（从句中的谓语动词用现在完成时have finished，表示将来完成时,决不可用will have finished）
If he comes back, please let me know.如果他回来了，请通知我。（从句中的谓语动词用comes back,表示一般将来时，决不可用will come back）
一、时间状语从句（adverbial clause of time）
1.由when, while, as引导的时间状语从句。例如：
When you think you know nothing, then you begin to know something.当你以为自己一无所知的时候，你就是在开始知道一些事物了。
When truth is buried under the ground it grows, it chokes, it gathers such an explosive force that on the day it bursts out , it blows up everything with it.当真理被埋在地下的时候，它在生长，它感到压抑，它蓄存着这么一种爆炸性力量，一旦冒出，它就会炸破一切！
Strike while the iron is hot. 趁热打铁。
Will you watch my clothes while I have a swim. 我游泳的时候，请你照看一下我的衣服。
when, while和as的区别
when引导的从句的谓语动词可以是延续性的动词，又可以是瞬时动词。并且when有时表示“就在那时”。
例如：
When she came in, I stopped eating.她进来时，我在吃饭。(瞬时动词)
When I lived in the countryside, I used to carry some water for him.当的住在农村时，我常常为他担水。（延续性的动词）
We were about to leave when he came in.我们就要离开，就在那时他进来了。
While引导的从句的谓语动作必须是延续性的，并强调主句和从句的动作同时发生（或者相对应）。并且while有时还可以表示对比。例如：
While my wife was reading the newspaper, I was watching TV. (was reading是延续性的动词，was reading和was watching同时发生)
I like playing football while you like playing basketball.我喜欢踢足球，而你喜欢打篮球。（对比）
As表示“一边……一边”，as引导的动作是延续性的动作，一般用于主句和从句动作同时发生；as也可以强调“一先一后。例如：
We always sing as we walk.我们总是边走边唱。（as表示“一边……一边”）
As we was going out, it began to snow.当我们出门时，开始下雪了。（as强调句中两个动作紧接着先后发生，而不强调开始下雪的特定时间）
as when while的辨析
as when while都表示主、从句动作同时发生，三者差异如下：
表示“一边。。。一边”的意思
as 强调两个动作同时进行，并表示对比时
用于发生时间较段时
when
1、还可以表示从句动词的动作在主几句动词的动作”之前 ”或”之后”发生。
2、when＝and then; at that moment (正在那个时候)
while 1、用于时间较长时
2、 强调两个动作同时进行，并表示对比时
有时这三个连词可以互换，有时不可以。
lIt was raining hard when (as) I got there.
我到那里时，正在下大雨。 ( 动作同时发生，when可换为as, 但不能换为while，因为get是点动词.)
lWhen I had read the article, he called me.
我看完这篇文章之后，她给我打了电话。( 从句动作发生在主句之前，注意时态表达，只能用when )
lWhen I got to the cinema, the film had begun.
(当)我到了电影院时，电影已经开演了。(从句的动作发生在主句之后，只能用when,并要注意时态)
while, as不能代替
lShe thought I was talking about her daughter, while, in fact, I was talking about my daughter.
他以为我在谈她女儿，然而，实际上在谈论我女儿。(表转折，对比，when, as都不能代替它)
lWhile the alien was buying a souvenir, the girl called the police.
外星人买纪念品时，那女孩给警察打了电话。(表示主句，从句的动作同时发生，while后引导的状语从句的动词必须是延续动词不能是点动词，因为它表示较长时间)
lMother was worried because little Alice was ill, especially as (when/ while) father was away.
妈妈担心，因为小爱丽丝病了，特别是他父亲不在家的时候。(此时as ,when, while可通用)
2.由before和after引导的时间状语从句。
注意before引导的从句不再用否定式的谓语，并且当before引导的从句位于主句之后，有时译成“就，才”。还要注意主句和从句之间的时间关系。当主句用将来时，从句总是用现在时；如果before引导的从句谓语用的是过去时，则主句动词多用过去完成时，这样以便体现动作发生的先后。After表示主句动作发生在从句动作之后。主句和从句的动作的时间关系正好与before引导的从句相反。例如：
It will be four days before they come back. 他们要过四天才能回来。
Einstein almost knocked me down before he saw me.爱因斯坦几乎把我撞倒才看到我。
After you think it over, please let me know what you decide.你仔细考虑过以后，告诉我你是怎样决定的。
After we had finished the work, we went home.完成工作之后，我们回家了。（从句用过去完成时，主句用一般过去时）
3.由till或until引导的时间状语从句。
till和until一般情况下两者可以互换，但是在强调句型中多用until。并且要注意的是：如果主句中的谓语动词是瞬时动词时，必须用否定形式；如果主句中的谓语动词是延续性动词时，用肯定或否定形式都可以，但表达的意思不同。例如：
I didn't go to bed until（till） my father came back.直到我父亲回来我才上床睡觉。
It was not until the meeting was over that he began to teach me English.直到散会之后他才开始教我英语。
4.由since引导的时间状语从句。
since引导的从句的谓语动词可以是延续性的动词，又可以是瞬时动词。一般情况下，从句谓语动词用一般过去时，而主句的谓语动词用现在完成时。但在It is ＋时间＋since从句的句型中，主句多用一般现在时。例如：
I have been in Beijing since you left. 自从你离开以来，我一直在北京了。
It is five months since our boss was in Beijing.我们老板离开北京有五个月了。
知识扩展
1. It is since从。。。以来多长时间了(因为since +从句或名词，表示一段时间)
It is five years since we met last time.从我们上次见面已经五年了。
2. It is +before…(。。。才)
It was a long time before I went to sleep again.
过了很长时间我才睡着。
5.由as soon as, immediately, directly, instantly, the moment, the instant, the minute, 等引导的时间状语从句。这些连词都表示“一……就”。例如：
I will go there directly I have finished my breakfast. 吃完早饭，我立即到那里去。
The moment I heard the news, I hastened to the spot.我一听到消息，马上赶到了出事地点。
As soon as I reach Canada, I will ring you up. 我一到加拿大，就给你来电话。
【注意】hardly(scarcely, rarely)…when / before, no sooner…than相当于as soon as之意。主句用过去完成时，从句用一般过去时。当hardly, scarcely, rarely和no sooner位于句首时，主句应用倒装语序。例如：
He had no sooner arrived home than he was asked to start on another journey. 他刚到家，就被邀请开始另一旅程。
No sooner had the sun shown itself above the horizon than he got out of bed to commence work.太阳刚从地平线上升起，他就起床劳动去了。
Hardly had I sat down when he stepped in.我刚坐下，他就进来了。
He had hardly fallen asleep when he felt a soft touch on his shoulder.这个阿拉伯人刚要入睡就感到肩膀上被轻轻一触。
6.由by the time引导的时间状语从句。
注意时态的变化：在一般情况下，如果从句的谓语动词用一般过去时，主句的谓语动词用过去完成时；如果主句的谓语动词用一般现在时，主句的谓语动词用将来完成时。例如：
By the time you came back, I had finished this book.到你回来时，我已经写完这本书了。
7.由each time, every time和whenever引导的时间状语从句。例如：
Each time he came to Harbin, he would call on me. 他每次来哈尔滨，总是来看我。
Whenever that man says“To tell the truth”, I suspect that he's about to tell a lie.每当那个人说“说实在话”的时候，我猜想他就要说谎了。
8.由as long as和so long as引导的时间状语从句。这两个连词表示“有多久……就多久”。例如：
You can go where you like as long as you get back before dark. 你可以随意到哪里去，只要在天黑以前回来就行。
I will fight against these conditions as long as there is a breath in my body! 只要我一息尚存，我就要反对这种境况。
二、地点状语从句：
地点状语从句 (adverbial clause of place)
地点状语从句一般由连接副词where, wherever等引导，已经形成了固定的句型，
要点: 由连词where和复合关系词wherever (=no matter where )引导.
例如：
句型1：Where＋地点从句，（there）＋主句。
【注意】此句型通常译成“哪里……哪里就……”；主句在从句后面时，there可用可不用；如果主句在从句的前面时，一般都不用there。例如：
Where there is no rain, farming is difficult or impossible.在没有雨水的地方，耕作是困难的，或根本不可能的。
They were good persons. Where they went, there they were warmly welcomed. 他们都是好人。因此他们走到哪里都受到热烈欢迎。
You should have put the book where you found it. 你本来应该把书放回原来的地方。
句型2：Anywhere/ wherever＋地点从句，＋主句。
【注意】anywhere本身是个副词，但是，常可以引导从句，相当于连词，意思相似于wherever, anywhere引导的从句可位于主句之前，也可以位于主句之后。 而wherever本身就是个连词，表示“在何处，无论何处”。例如：
Wherever the sea is , you will find seamen.有海就有海员。
三、条件状语从句：
要点： 表示状语从句由连词if, unless (=if not) 引导。
1.If it doesn’t rain tomorrow, we will go hiking.
如果明天不下雨, 我们就去远足.
2.You will get good grades if you study hard.
如果你努力学习,就会取得好成绩.
3.I will go to the party unless he goes there too.
我不会去参加聚会的, 除非他也去.(如果他不去,我也不去.)
4.You will be late unless you leave immediately.
如果你不马上走,你将会迟到的.(=If you don’t leave immediately, you will be late.)
难点提示：用条件状语从句时要注意时态的正确使用,当主句是将来时的时候,从句要用一般现在时.
lHe will not leave if it isn’t fine tomorrow.
一般将来时， 一般现在时
lThey are going to have a picnic if it doesn’t rain next week.
一般将来时, 一般现在时
四、原因状语从句：
要点: 由连词because, since, as引导, 也可由for, now that 等词引导
1.I didn’t go to school yesterday because I was ill.
我昨天没去上学，因为我生病了。
2. Since everybody is here, let’s begin our meeting.
既然大家都来了, 让我们开始开会吧.
难点——because , since , as , for,辨析
1） because语势最强，用来说明人所不知的原因，回答why提出的问题。当原因是显而易见的或已为人们所知，就用as或 since。
I didn’t go, because I was afraid.
Since /As the weather is so bad, we have to delay our journey.
2） 由because引导的从句如果放在句末，且前面有逗 号，则可以用for来代替。但如果不是说明直接原因，而是多种情况加以推断，就只能用for。
He is absent today, becaus e / for he is ill.
He must be ill, for he is absent today.
五、目的结果状语从句：
要点： 目的状语从句由连词that, so that, so…that , in order that 引导。
结果状语从句由连词( so )that, so…that, such…that, so much/many…that引导。
1.so…that 如此…以至于
The scientist’s report was so instructive that we were all very excited.
科学家的报告很有启发性，我们感到很兴奋。
He always studied so hard that he made great progress.
他总是那么努力，结果他取得了很大的进步。
2.so that 以至, 以便
I’ll run slowly so that you can catch up with me. (目的)
我将慢慢跑以至你能赶上我。
I opened the window so that fresh air might come in. (目的)
我把窗户打开以使新鲜空气可以进来。
3. such…that 如此。。。以至
It’s such nice weather that all of us want to go to the park.
天气是如此的好，我们大家都想去公园玩。
4.in order that=so that:为了
We shall let you know the details soon in order that you can/may make your arrangements.
不久我们将会让你知道详情,以便你们能够做出安排。(目的)
5.比较：so和 such
其规律由so与such的不同词性决定。such 是形容词，修饰名词或名词词组，so 是副词，只能修饰形容词或副词。 so 还可与表示数量的形容词many, few, much, little连用，形成固定搭配。
so foolish such a fool
so nice a flower such a nice flower
so many / few flowers such nice flowers
so much / little money. such rapid progress
so many people such a lot of people
（ so many 已成固定搭配，a lot of 虽相当于 many，但 a lot of 为名词性的，只能用such搭配。）
so…that与such…that之间的转换既为 so与such之间的转换。
The boy is so young that he can’t go to school.
He is such a young boy that he can’t go to school
难点
+形容词或副词
+形+a(an)+单数可数名词
so +many 或few+复数可数名词 +that
+much或 little+不可数名词
so that ,such…that 都可以in order that两者皆可引导目的地状语从句和结果状语从句，
当他们引导目的状语从句时，从句的谓语里常常有can, could, may, might, will, would等次。
so +adj或adv.+ that， such +n.+ that 以上两种句型都表示结果,其中so为副词,后接形容词，副词原型，当可数名词前有many, few；不可数名词前有much, little修饰时，应采用句型：so many (few, much, little )+n. 。 such为形容词, 后只能接名词。这名词既可以地可数的，也可以是不可数的。如果这名词是可数,单数,则必须在名词前敬爱冠词a(an). 常见的形式是:such a (beautiful)garden, such(nice)people.
1。I’ve had so many falls that I’m black and blue all over.
我跌了很多跤，浑身数摔得清一块紫一块.
2。there are so few notebooks that I can’t give you any.
笔记本太少了,我一本也给不了你.
3。It is such nice weather that I’d like to take a walk.
天气是如此只好,以至于我想去散散步.
六、让步状语从句：
要点: 表示让步的状语从句由连词 though, although引导.
难点：
lthough, although当虽然讲, 都不能和but连用. Although,(though)…but的格式是不对的.但是他们都可以同yet (still) 连用. 所以thought (although)…yet(still)的格式是正确的.
Wrong: Although he is rich but he is not happy.
Right : Although he is rich, yet he is not happy.
虽然他很富有, 然而他并不快乐.
Right : Although we have grown up, our parents treat us as children.
Right : Although we have grown up, our parents still treat us as children.
尽管我们已经长大了,可是我们的父母仍把我们看作小孩.
although, though 辨析
although 不能though 那样用作副词, 放在句末表示强调时要用even though.
1。He is looking fit, though.
但是,他看上去很健康. 考点
2。Even though I didn’t under a word, I kept smiling.
尽管我一个字也不懂，我还是一直微笑着。
3。He is quite experienced, he is young, though.
尽管他很年轻，他很有经验。
典型例题
1） ___she is young, she knows quite a lot.
A. When B. However C. Although D. Unless
答案：C。意为虽然她很年轻，却知道许多。
2) as, though 引导的倒装句
as / though引导的让步从句必须表语或状语提前（形容词、副词、分词、实义动词提前）。
Child as /though he was, he knew what was the right thing to do.
= Though he was a small child, he knew what was the right thing to do.
注意：
a. 句首名词不能带任何冠词。
b. 句首是实义动词，其他助动词放在主语后。如果实义动词有宾语和状语，随实义动词一起放在主语之前。
Try hard as he will, he never seems able to do the work satisfactorily.
= Though he tries hard, he never seems…
虽然他尽了努力，但他的工作总做的不尽人意。
3) ever if, even though. 即使
We’ll make a trip even though the weather is bad.
4) whether…or- 不管……都
Whether you believe it or not, it is true.
5) "no matter +疑问词" 或"疑问词+后缀ever"
No matter what happened, he would not mind.
Whatever happened, he would not mind.
替换：no matter what = whatever
no matter who = whoever
no matter when = whenever
no matter where = wherever
no matter which = whichever
no matter how = however
注意：no matter 不能引导主语从句和宾语从句。
（错）No matter what you say is of no use now.
（对）Whatever you say is of no use now.
你现在说什么也没用了。(Whatever you say是主语从句)
（错）Prisoners have to eat no matter what they’re given,
（对）Prisoners have to eat whatever they’re given. 囚犯们只能给什么吃什么。
七、比较状语从句：
要点：比较状语从句主要运用于形容词和副词的原级，比较级及最高级的句子之中。
原级
1. as…as 和。。。一样
Jack is as tall as Bob.
捷克和汤姆一样高。
2. not so(as)…as …和不一样
She is not so(as)outgoing as her sister.
她不如她姐姐外向。
比较级
more…than (更)
This book is more instructive than that one.
这本书比那本书由教育意义。
最高级
1.The most…in/of
This book is the most interesting of the three.
这本书是三本中最有趣的。
2. the + 形容词+est…of/in
This road is the busiest street in our city.
这条路是我们城市最繁忙的街道。
知识扩展
no more than只不过(嫌少的意思)
1。I have no more than two pens.
我只有两支笔。
2。It’s no more than a mile to the shops.
去商店不过一英里。
not more than不如。。。；(前者不如后者)
1。Jack is not more diligent than John.
捷克不如约翰勤奋。
2。one of the + 名词(复数)….之一(用于最高级)
Han Mei is one of the best students in our school.
韩梅是我们学校最好的学生之一。
八、方式状语从句：
方式状语从句通常由as, (just) as…so…, as if, as though引导。
1） as, (just) as…so…引导的方式状语从句通常位于主句后，但在(just) as…so…结构中位于句首，这时as从句带有比喻的含义，意思是"正如…"，"就像"，多用于正式文体，例如：
1。Always do to the others as you would be done by.
你希望人家怎样待你，你就要怎样待人。
2。As water is to fish, so air is to man.
我们离不开空气，犹如鱼儿离不开水。
3。Just as we sweep our rooms, so we should sweep backward ideas from our minds.
正如打扫房屋一样，我们也要扫除我们头脑中落后的东西。
2） as if, as though
两者的意义和用法相同，引出的状语从句谓语多用虚拟语气，表示与事实相反，有时也用陈述语气，表示所说情况是事实或实现的可能性较大。汉译常作"仿佛……似的"，"好像……似的"，例如：
1。They completely ignore these facts as if (as though) they never existed.
他们完全忽略了这些事实，就仿佛它不存在似的。（与事实相反，谓语用虚拟语气。）
2。He looks as if (as though) he had been hit by lighting.
他那样子就像被雷击了似的。（与事实相反，谓语用虚拟语气。）
3。It looks as if the weather may pick up very soon.
看来天气很快就会好起来。（实现的可能性较大，谓语用陈述语气。）
说明：as if / as though也可以引导一个分词短语、不定式短语或无动词短语，例如：
1。He stared at me as if seeing me for first time.
他目不转睛地看着我，就像第一次看见我似的。
2。He cleared his throat as if to say something.
他清了清嗓子，像要说什么似的。
3。The waves dashed on the rocks as if in anger.
波涛冲击着岩石，好像很愤怒。
九、状语从句在写作中的运用：
写作中能合理、正确地使用状语从句，不但能地道的表达英文习惯，而且还能使文体结构更加严谨、美观。例如下文：
My hobby
The hobby I enjoy most is fishing.
I started fishing (1)when I was five years old. I’ll never forget the day (2)when my father first took me fishing with him. On that day, I was holding a fishing rod (3)when a fish suddenly started pulling on the line. (4)I was so shocked that I fell into the water. But experience didn’t put me off and I have been fishing ever since.
Now I still go fishing with my father. And we often go out on Sundays and spend the whole day fishing in the river.
(1)是由when引导的时间状语从句，这列从句的使用频率很高。
(2)句是由I’ll never forget the day .及when my father first took me fishing with him.两局组成。When在从句中做时间状语。
(3)句也是由when 引导的时间状语从句。When 常与suddenly 连用，主句常用过去进行是。译为 “正在……, 忽然……”.
(4)是以 so…that… (太…..一直于……)引导的结果状语从句.
参考资料：http://baike.baidu.com/view/84572.htm#2