八年级下册状语从句讲解及练习

状语从句

用来修饰主句中的动词，副词和形容词的从句叫状语从句。根据其含义状语从句可分为时间状语从句，地点状语从句，条件状语从句，原因状语从句，结果状语从句，比较状语从句，目的状语从句，让步状语从句。

1. 时间状语从句

(1)时间状语从句常用when, as, while, before, after, since, till, until, as soon as等连词来引导。. It was raining hard when got to school yesterday.

While he was doing his homework, the telephone rang.

(2)在时间状语从句里，通常不用将来时态，用现在时态表示将来的动作或状态。.

I’ll ring you up as soon as I get to New York.

(3)在带有till或until引导的时间状语从句的主从复合句里，如果主句用肯定式，其含义是“一直到……时”，谓语动词只能用延续性动词。如果主句用否定式，其含义是“直到……才……”, “在……以前不……”, 谓语动词可用瞬间动词。.

The young man read till the light went out.

Let’s wait until the rain stops.

2. 条件状语从句

(1)条件状语从句通常由if, unless引导。.

What shall we do if it snows tomorrow?

Don’t leave the building unless I tell you to.

(2)在条件状语从句里，谓语动词通常用现在时态表示将来的动作或状态。.

I’ll help you with your English i f am free tomorrow.

He won’t be late unless he is ill.

(3)“祈使句+ and (or)+ 陈述句” 在意思上相当于一个带有条件状语从句的复合句。.：Hurry up, or you’ll be late.

=If you don’t hurry up, you’ll be late.

Study hard and you will pass the exam.

=If you study hard, you will pass the exam.

3. 原因状语从句

(1)原因状语从句通常由because, since, as引导。.

He didn’t come to school because he was ill.

As it is raining, we shall not go the zoo.

Since you can’t answer the question, I’ll ask someone else.

(2)because表示直接原因，语气最强。Because引导的原因状语从句多放在主句之后。回答由why提出的问题，只能用because。As和since语气较弱，一般用来表示明显的原因。由as和since引导的原因状语从居多放在句首。.------Why aren’t going there?

------Because I don’t want to.

As he has no car, he can’t get there easily.

Since we have no money, we can’t buy it.

(3)because和so不能同用在一个句子里。

4. 结果状语从句

(1)结果状语从句由so…that, such…that, so that引导。.

He is so poor that he can’t buy a bike for his son.

She is such a good teacher that everybody likes her.

My pencil fell under the desk, so that I couldn’t see it.

(2)so…that语such...that可以互换。.

在由so...that引导的结果状语从句中，so是副词，与形容词连用。其结构是: “...so + 形容词（副词）+ that + 从句”。He was so glad that he couldn’t say a word.

The hall is so big that it can hold 2,000 people.

Mother lives so far away that we hardly ever see her.

5. 比较状语从句

比较状语从句通常由as…as, 比较级+ than…等连词引导。.

Tom runs faster than John does. This classroom is as big as that one.

6. 目的状语从句

(1)目的状语从句通常由so that, in order that引导。.

We started early so that we could catch the first train.

He studies hard so that he could work better in the future.

We used the computer in order that we might save time.

(2)so that既可引导目的状语从句，又可引导结果状语从句。区别这两种从句的办法有两个：1)目的状语从句里往往带有情态动词can, could, may, might等。2)从意思上看，目的状语从句往往表示的目的很明确。.

Speak clearly so that they may understand you. (目的状语从句)

Jack is badly ill so that he has to rest. (结果状语从句)

7. 让步状语从句

(1)让步状语从句通常由although, though等连词引导。

Though he is young, he knows a lot.

Although I am tired, I must go on working.