各种从句的构成和意义 ---名词性从句和状语从句

状语从句(The Adverbial Clause)
在复合句中起状语作用的从句叫状语从句,可表示时间、地点、原因、目的、结果、条件、让步等意义。

I. 时间状语从句
时间状语从句通常有when(当……时候)，whenever(在任何时候, 每当)，as(当……时候，随着)，while(在……期间，与……同时)，before(在……以前)，after (在……之后)，since(自从……以来)，as soon as (一……就)，until( till) (直到……)等连词引导：
如：
e.g.A well-mannered person never laughs at people when they are in trouble.
e.g.Whenever the manager is out, his assistant signs the letters.
e.g.The Premier is now at the door greeting his guests as they arrive.
e.g.While Betty was getting dressed, she kept looking at the clock.
e.g.He talked to the blind girl as the train pulled out of the station.
e.g.The fields don’t require irrigation until weather is dry in the summer.

II. 地点状语从句
地点状语从句通常由where (哪里，在……地方)，wherever( 无论什么地方)等
连词引导：
e.g.When previewing a new lesson, make marks where you have questions.
预习新课时，在你有问题时做个记号。
e.g.Please take this suitcase and put it wherever you can find enough space.
请提着这个小箱子，找一个有空的地方放着。

III. 原因状语从句
原因状语从句通常由because (因为)，since(既然，由于)，as (因为，由于)等连词引导：
e.g.We didn’t go to that restaurant again because the service was poor.
因为服务太差，我们不再去那个餐馆吃饭了。
e.g.Since numerous objections were made, the plan was not accepted.
既然有很多人反对，计划就没有通过。
e.g.As Venus is the brightest planet, we can sometimes see it in the daytime.
由于金星是最光亮的行星，我们有时白天能看到它。
注：because 表示有必然的因果关系，“原因”意味最强，since表示一种间接或附带的原因，有汉语“既然”的意义，较because稍弱。as 表示“原因”的意味更弱。

IV.目的状语从句
目的状语从句通常由that (为了，以便)，so that(为了，以便)，in order that(为了，以便)，lest (以免，以防)等连词引导：
e.g.Bring the picture closer that I can see it better.
e.g.The material for building the bridge must be very strong so that it may not break in use.为使桥梁不致在使用中断裂，建造桥梁的材料强度必须非常高。
e.g.He checked all his figures again in order that the report might be as accurate as possible.
他把所有的数字又检查了一次，为的是使报告尽可能准确。
e.g.Please remind me of it again tomorrow, lest I (should) forget.
请你明天再提醒我一下，免得我忘记。

V. 结果状语从句
结果状语从句通常由so that(结果,以至), so…that(如此…以致),such…that(这样的…以致)
等连词引导,表示结果。
e.g.Steel has many advantages so that it is widely used in industry.
e.g.So many people applied for the job that he spent the entire day giving interviews.
有那么多人申请这份工作,以致他花了一整天时间进行面试。
e.g.It was such a worthy cause that we contributed a generous amount of money.
这项事业很有价值,因此我们捐赠了大量款项.
注: so that 既可表示“目的”，也可表示“结果”的含义。表示“目的”时,从句中通常出现may(might), can (could), should, would等情态动词, 但表示“结果”的从句有时也可用情态动词,所以有时需要根据上下文来判断从句所表示的逻辑关系。

VI.条件状语从句
条件状语从句通常由if (如果),unless(除非,若不),suppose(supposing)(假设),provided(假若), in case(如果),as(so)long as (只要)等连词引导，表示假设条件。
e.g.If the car is powered by electricity, there will be less pollution.
e.g.Unless you study hard, you won’t get a scholarship.
e.g.Provided/Suppose/Given there is no opposition, we shall hold the meeting here.
假若没有反对意见,我们将在这儿开会.
e.g.The mass meeting will be put off in case it rains.
万一下雨,群众大会将延期.