专题十一状语从句状语从句在高考试题中由于其他从句的干扰，以及倒装句，强调句的介入，使得状语从句更为复杂。

状语从句是一种副词性从句，通常由一个从属连词或一个起连词作用的词组引导。

状语从句1. 时间状语从句常见的连词(组)：when, while, as, before, after, once, till, until, as soon as, now that, hardly ...when, scarcely ...when, no sooner ...than等。

可以引导时间状语从句的副（介）词（短语）或名词短语：directly, instantly, immediately, by the time, the moment, the second, the minute, the instant, every time, each time, next time, the last time等。

注意点如下：(1) when, while, as引导的时间状语从句as表示“当……的时候”，往往和when/ while通用，但它着重强调主句与从句的动作或事情同时或几乎同时发生。

when(at or during the time)既可以表示在某一点的时候，又可以表示在某一段时间内，主句与从句的动作或事情可以同时发生也可以先后发生。

while强调一段时间，仅表示从句和主句的动作同时发生，并且有延续意义，该从句中的动词一般要用延续性动词，从句中常用过去进行时态或一般过去时态；当when表示a period of time时，两者可以互换。

She came up as I was cooking.(同时)在我做饭时，她走了过来。

When we were at school, we went to the library every day.(在一段时间内)当我们在学校时，每天都去图书馆。

While they were watching TV, I was preparing myself for the coming examination.他们在看电视，而我在为即将到来的考试做准备。

Strike while the iron is hot. 趁热打铁。

( 不可用as或when，这里的while意思是“趁……”)when，while，as显然都可以引导时间状语从句，但用法区别非常大。

一、when可以和延续性动词连用，也可以和短暂性动词连用；而while和as只能和延续性动词连用。

① Why do you want a new job when you've got such a good one already？（get为短暂性动词）你已经找到如此好的工作，为何还想再找新的？②Sorry，I was out when you called me．（call为短暂性动词）对不起，你打电话时我刚好外出了。

③Strike while the iron is hot．（is为延续性动词，表示一种持续的状态）趁热打铁。

④ The students took notes as they listened．（listen为延续性动词）学生们边听课边做笔记。

二、when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while和as从句的谓语动作必须是和主句谓语动作同时发生。

1．从句动作在主句动作前发生，只用 when。

①When he had finished his homework，he took a short rest．（finished先发生）当他完成作业后，他休息了一会儿。

②When I got to the airport，the guests had left．（got to后发生）当我赶到飞机场时，客人们已经离开了。

2．从句动作和主句动作同时发生，且从句动作为延续性动词时，when，while，as都可使用。

①When ／While ／As we were dancing，a stranger came in．（dance为延续性动词）当我们跳舞时，一位陌生人走了进来。

②When ／While ／As she was making a phonecall，I was writing a letter．（make为延续性动词）当她在打电话时，我正在写信。

3．当主句、从句动作同时进行，从句动作的时间概念淡化，而主要表示主句动作发生的背景或条件时，只能用 as。

这时，as常表示“随着……”；“一边……，一边……”之意。

① As the time went on，the weather got worse．（as表示“随着……”之意）② The atmosphere gets thinner and thinner as the height increases．随着高度的增加，大气越来越稀薄。

③As years go by，China is getting stronger and richer．随着时间一年一年过去，中国变得越来越富强了。

④The little girls sang as they went．小姑娘们一边走，一边唱。

⑤The sad mother sat on the roadside，shouting as she was crying．伤心的妈妈坐在路边，边哭边叫。

4．在将来时从句中，常用when，且从句须用一般时代替将来时。

①You shall borrow the book when I have finished reading it．在我读完这本书后，你可以借阅。

②When the manager comes here for a visit next week，I'll talk with him about this．下周，经理来这参观时，我会和他谈谈此事。

三、when用于表示“一……就……”的句型中（指过去的事情）。

sb．had hardly（＝scarcely） done sth．when．．．＝Hardly ／ Scarcely had sb．done sth．when．．．①I had hardly ／scarcely closed my eyes when someone knocked at the door．＝Hardly ／ Scarcely had I closed my eyes when someone knocked at the door．我刚一闭上眼，就有人在敲门了。

②I had hardly ／scarcely entered my room when the telephone rang．＝Hardly ／Scarcely had I entered my room when the telephone rang．我刚一走进房门，电话就响了。

(2) before引导状语从句时的常见重点句型①It will (not) be ...before ...还要……才，要不了多久就……It was (not) ...before ... 过了……才(没多久就……)It was a long time before I got to sleep.过了好长时间我才睡着了。

It wasn t long before he told me about the news.没多久他就告诉了我那条新闻。

②不等……就……；在……之前就……The telephone rang off before I could answer it.我还没来得及接电话，电话就挂断了。

③刚……就……He hardly entered the room before he heard the telephone ring.他刚进屋电话铃就响了。

④先……再……You can have a few days to think about it before you make your decision.做决定之前你还有几天时间考虑。

(3)since 引导的从句用延续性动词的过去式（包括过去完成时）时，则从句的动作已经结束,从句意思是否定的。

如果从句的动词是延续性动词的现在完成时态，则从句意思是肯定的。

He has never been to see me since I was ill.我病愈后，他一直未来看我。

（不再生病了）He has never been to see me since I have been ill.我病了，他一直未来看我。

I haven t heard from him since he lived here.自他从这里搬走，我就没有收到他的信。

（不住在这儿了）(4) till, until如果till与until用在肯定句中时，则主句中谓语动词部分所表示的动作或状态一直延续到某时或某个动作发生时才结束。

注意它的倒装句和强调句。

I didn t recognize she was my classmate until she took off her dark glasses.=Not until she took off her dark glasses did I recognise she was my classmate=It was not until she took off her dark glasses that I recognised she was my classmate.直到她摘下墨镜，我才认出她是我的同学。

2. 原因状语从句引导原因状语从句的常见连词或短语：as, because, since, now that, considering that, seeing that(鉴于……)。

注意以下几点：(1) because, since, as, for, now thatbecause语气最强，用于回答why的提问，可与强调词only, just 以及否定词not 连用。

但不可以与so连用。

since 引导的从句语气次于because引导的从句，常表示稍加分析后而推断出的原因，或指人们已知的事实，比as正式一些,常置于句首。

as 语气最弱，其原因只是对结果的附带说明，一般放在句首。

for虽然解释为“因为”但只是一个并列连词，它也常引导句子表示原因，但不是原因状语从句，它是一个并列句。

for所提供的理由是一种补充性的说明，表示推测的理由。

now that意为“既然，由于”。

表示由于人们已知的事实或正在发生的事而产生某个结果。

He failed because he was careless.他因粗心而失败了。