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一、定義
顧名思義，狀語從句就是指句子中的狀語原本是由單詞或短語來充當(dāng)?shù)?，但?dāng)狀語是由句子來充當(dāng)時(shí)，這個(gè)充當(dāng)狀語的句子就叫狀語從句。如：
He left the party at eight.
He left the party when it was eight.第一句中的at eight是時(shí)間狀語，是由短語來充當(dāng)?shù)摹?BR> 第二句中的when it was eight也是時(shí)間狀語，但是由句子來充當(dāng)?shù)模@個(gè)句子就叫(時(shí)間)狀語從句。
二、分類
英語里的狀語總共有九種，即：時(shí)間、地點(diǎn)、原因、結(jié)果、目的、條件、比較、方式、讓步。而英語里的狀語從句也因此包括這九種，接下去我們就一一來梳理這九種從句的用法。需要注意的是，狀語從句的學(xué)習(xí)其實(shí)就是有關(guān)連接這些狀語從句的連接副詞的學(xué)習(xí)。
三、時(shí)間狀語從句
常連接時(shí)間狀語從句的連接詞有：
when, while, as;
before, after;
as soon as, hardly...when..., no sooner...than...;
till, until;
since;
by, by the time, by the end of。
(一)when、while和as的用法
三者都表示“當(dāng)...時(shí)候”，需要注意的是：
1、當(dāng)所要描述的動(dòng)作或狀態(tài)發(fā)生的時(shí)間是現(xiàn)在時(shí)間時(shí)
1)when要采用“主將從現(xiàn)”的原則，即：主句謂語動(dòng)詞采用一般將來時(shí)，從句謂語動(dòng)詞采用一般現(xiàn)在時(shí)。如：
When he comes, I will tell him the good news.需要注意的是，此時(shí)的從句謂語動(dòng)詞雖然采用的是一般現(xiàn)在時(shí)，但其實(shí)是表將來的。如上句中的he comes，他其實(shí)還沒來。
此外，主句也有可能是祈使句或是含有情態(tài)動(dòng)詞的句子。如：
When he comes, please tell him the good news.
When he comes, you can tell him the good news.2)as的用法跟when差不多，但其主句謂語動(dòng)詞也可以使用一般現(xiàn)在時(shí)。如：
A sudden chill of horror sweeps over her as she feels the drip of saliva upon her hand. (當(dāng)她感覺到滴到她雙手上的唾液時(shí)，恐怖的寒栗突然遍布了她全身。)3)while所在的句子主從句的謂語動(dòng)詞一般都采用現(xiàn)在進(jìn)行時(shí)。如：
While my mother is cooking in the kitchen, my father is working in the garden.2、當(dāng)所要描述的動(dòng)作或狀態(tài)發(fā)生的時(shí)間是過去時(shí)間時(shí)
1)when所在的從句謂語動(dòng)詞一般采用一般過去時(shí)，主句謂語動(dòng)詞采用過去進(jìn)行時(shí)或是一般過去時(shí)。如：
When he entered the room, she was playing the piano.
But when I returned the door was open.
需要注意的是，when也有可能表示“正在這時(shí)”。如：
I was walking in the park, when a little child bumped into me. (我正在公園里散步，這時(shí)一個(gè)小孩撞到了我懷里。)2)as與while的用法差不多，即：as和while所在的句子的謂語動(dòng)詞一般用過去進(jìn)行時(shí)，而另外一個(gè)句子的謂語動(dòng)詞則采用過去進(jìn)行時(shí)或一般過去時(shí)。如：
As/While the royal visitors were passing by, the crowd burst into cheers.
As/While she was reading in the study, he was watching TV in the living room.
(二)before和after的用法
before表示“在...之前”，after表示“在...之后”。使用時(shí)要注意要描述的動(dòng)作或狀態(tài)時(shí)基于現(xiàn)在時(shí)間還是過去時(shí)間。
1、基于現(xiàn)在時(shí)間
這時(shí)，其用法基本遵循時(shí)間狀語從句的“主將從現(xiàn)原則”，即before或after所在的從句謂語動(dòng)詞采用一般現(xiàn)在時(shí)，其主句謂語動(dòng)詞采用一般將來時(shí)。如：
Before the guests come, we will have to clean the house.
After he comes, we will set out for Shanghai.2、基于過去時(shí)間
這時(shí)，before所在的從句謂語動(dòng)詞要采用一般過去時(shí)，其主句謂語動(dòng)詞要采用過去完成時(shí)，而after所在的從句謂語動(dòng)詞要采用過去完成時(shí)，其主句謂語動(dòng)詞要采用一般過去時(shí)。如：
Before it began to rain, she had already arrived home.
After she had arrived home, it began to rain.
(三)“一...就...”的表達(dá)
英語里常用來表“一...就...”的結(jié)構(gòu)主要有：as soon as, hardly...when..., no sooner...than...。、
1、as soon as
as soon as既可以用在現(xiàn)在時(shí)間中，也可以用在過去時(shí)間中。當(dāng)用在現(xiàn)在時(shí)間中時(shí)，遵循“主將從現(xiàn)”的原則;當(dāng)用在過去時(shí)間中時(shí)，as soon as所在的從句謂語動(dòng)詞采用一般過去時(shí)，其主句謂語動(dòng)詞采用一般過去時(shí)或過去完成時(shí)(如果要強(qiáng)調(diào)主從句謂語動(dòng)作的連續(xù)性很強(qiáng)，則采用一般過去時(shí))。如：
現(xiàn)在時(shí)間：As soon as she comes to the party, we will give her a big surprise.
過去時(shí)間：As soon as he got to the station, the train left/had left.2、hardly...when...和no sooner...than...
這兩個(gè)句型都表示“一...就...”，而且用法都差不多，即when和than所在的從句謂語動(dòng)詞采用一般過去時(shí)，其主句謂語動(dòng)詞采用過去完成時(shí)。如：
He had hardly arrived at school when the class began.
He had no sooner arrived at school than the class began.需要注意的是，hardly有時(shí)可以換成scarcely或rarely或barely。
3、特殊表達(dá)
英語中用來表達(dá)“一...就...”的結(jié)構(gòu)還有：the moment/instant/minute/second...;immediately/instantly/directly...;at/on等。如：
He came directly I called.
The moment she gets off the bus, we will give her a big hug.
On hearing the news, he burst into cries.
(四)till和until
都表示“直到...時(shí)候”，兩者一般可以相互替換，但till多用于肯定句，until多用于否定句。如：
She will stay in the office till he comes back.
She won't leave the office until he comes back.需要注意的是，until常與not搭配使用，而且會(huì)用在強(qiáng)調(diào)句中。如：
He didn't arrive until the film had already begun.
It was not until the film had already begun that he arrived.
(五)since
當(dāng)since用來引導(dǎo)時(shí)間狀語從句時(shí)，意思是“自從...以來”，其往往被當(dāng)作是主句謂語動(dòng)詞要采用完成時(shí)的標(biāo)志性時(shí)間狀語。如：
Since he was born, he has lived here for over eighty years.
Since we last met, we haven't seen each other for more than ten years.
(六)by、by the time和by the end of
這組結(jié)構(gòu)都表示“到...時(shí)候?yàn)橹埂?，其主句謂語動(dòng)詞一般都要采用完成時(shí)。需要注意的是，這些結(jié)構(gòu)后面所接的時(shí)間不同，主句謂語動(dòng)詞就要采用不同的完成時(shí)態(tài)。
1、后接將來時(shí)間
這時(shí)，主句謂語動(dòng)詞一般要采用將來完成時(shí)或?qū)硗瓿蛇M(jìn)行時(shí)。如：
He will have read ten books by next Friday this month.
She will have been learning English for ten years by the end of this term.
They will have already left by the time she comes.2、后接過去時(shí)間
這時(shí)，主句謂語動(dòng)詞一般要采用過去完成時(shí)。如：
They had learned English for ten years by last Saturday.
The students had already left the party by the time she arrived.
We had worked on the bridge for two years by the end of last month.