原因状语从句知识讲解

1、定义：在句中用来说明主句原因的句子叫原因状语从句。

2、常用引导词: because(因为), as (由于), since (既然), now (that) (既然)

3、时态：原因状语从句一般都是根据实际情况选用适当的时态。通常是主过从

过，主现从现。

4、because, since和as的区别：

1) because引导的原因状语从句一般放于主句的后面，because从句位于句首时要用逗号分开，放在句末时，可不用逗号分开。because表示直接原因，语气最强，最适合回答why引导的疑问句。because of 也表示原因，但它后面不接从句, 只能接名词, 代词或动名词。注意：because 和so 不可同时出现在一个句子里。

①I do it because I like it. = I like it so I do it.

②We went by bus because it was cheaper. = It was cheaper so we went by bus.

③He can’t go to school because of his illness.

2) since引导的原因状语从句一般放于主句之前表示已知的、显然的理由(通常被翻

译成“既然”= now that )，较为正式，语气比because弱。

①Since you are free today, you had better help me with my mathematics.

②Since you don't trust him, you should not employ him.

③Now (that) you are grown up, you should not rely on your parents.

3) as引导原因状语从句时表示附带说明的“双方已知的原因”，含有对比说明的意味，

语气比since弱，较为正式，位置较为灵活(常放于主句之前)。

①As it is raining, you’d better take a taxi.

②As you are tired, you had better rest.

③I went to bed early, as I was exhausted.

4) for引导的是并列句表示原因但并不说明主句行为发生的直接原因，只提供一些辅

助性的补充说明，for引导的并列句只能放于主句之后并且必须用逗号将其与主句隔开。

①He could not have seen me, for I was not there.

②He seldom goes out now, for he is very old.

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1、定义：在句中用来作目的状语的句子叫目的状语从句。

2、常用引导词: so that (以便),in order that (以便)

3、时态：目的状语从句一般都是根据实际情况选用适当的时态。也通常是主过从过，主现从现。

4、目的状语从句应注意以下：

1) 目的状语从句中常含有can, could, may, might, should, will, would等情态动词。

I got up early so that I could catch the first bus.

2) 在口语中so可以引导目的状语从句。

We'll sit nearer the front so we can hear better.

3) in order that与in order to的区别：

①in order that +从句= so that +从句

②in order to+动词原形= so as to +动词原形(不放于句首) = to+ 动词原形

I get up early in order to catch the early bus.

= I get up early in order that I can catch the early bus.

四、结果状语从句：

1、定义：在句中用来作结果状语的句子叫结果状语从句。

2、常用引导词: so … that (如此…以致…),such … that (如此…以致…)

3、时态：结果状语从句一般都是根据实际情况选用适当的时态。也通常是主过从过，主现从现。

4、结果状语从句的句型：

结果状语从句的从句部分是补充说明主句中谓语动词发生的结果的，通常位于主句之后。结果从句中通常不用情态助动词，但must, can, could除外。结果状语从句其规律由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。

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1) so + 形/ 副+ that从句

① The boy is so young that he can't go to school.

② He speaks so fast that no one can catch him.

2) so + many/few（+复名）+ that从句

There are so many picture-story books that the boy won't leave.

3) so + much/ little（+ 不可数名词）+that从句

He gave me so little time that it was impossible for me to finish the work on time.

4) so+ 形+ a/an+ 单名+ that从句

It was so hot a day that they wanted to go swimming.

5) such+ a/an+ 形+单名+ that从句= so+ 形+ a/an+单名+ that从句

He is such a young boy that he can't go to school.

= He is so young a boy that he can't go to school.

6) such+ 形+ 复名/不可数名词+ that从句

① They are such fine teachers that we all hold them in great respect.

② It is such nice weather that I would like to go to the beach.

5、结果状语从句与简单句的转换：

1) so… that (从句为肯定句) = … 形/副+ enough + (for sb.) to do sth.

He is so old that he can go to school alone.

= He is old enough to go to school alone.

2) so… that (从句为否定句) = … too + 形/副+ (for sb.) to do sth.

The problem is so hard that I can’t work it out.

= The problem is too hard for me to work out.

= The problem isn’t easy enough for me to work out.

五、让步状语从句

1、定义：在句中用来表示“退一步说……”的句子叫让步状语从句。

2、常用引导词: although (虽然) = though（尽管，即使），no matter+疑问词=疑问词-ever（无论…），even if = even though（即使），whether... or …(不管是…还是…)等。

3、时态：让步状语从句的时态一般采用主过从过，主将从现的原则。

4、让步状语从句的注意点：

1) although/ though 不可与but连用(二者只选其一)，但可与still / yet连用。

① Although / Though he is very old, still he is quite strong.

② Although he was ill , he went to school. = He was ill but he went to school.

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