从句与非谓语动词之间的转换

非谓语动词与从句的相互转换

一、如何把复合句改为简单句呢?

首先，分清主从复合句，先要取消从句，一般要把引导从句的连词去掉。例如：

When he was waiting for the bus, he saw a dog.

→Waiting for the bus, he saw a dog.

其次，如果从句的谓语动词是主动式，就要把谓语动词改为现在分词;如果从句的谓语动词是被动式就要把谓语动词改为过去分词;并且要注意时态的变化。

例如：

1. After he had finished his homework , he went home.

→Having finished his homework, he went home.

2. Because I have promised to meet my friend at the airport, I can’t accept your invitation.

→Having promised to meet my friend at the airport, I can’t accept your invitation.

3. As he was deeply moved by the story, he couldn’t keep back his tears.

→Deeply moved by the story, he couldn’t keep back his tears.

4. As he was born into a tenant farmer family, he had only two years of schooling.

→Born into a tenant farmer family, he had only two years of schooling.

另外，还要注意在用分词短语作状语时，它逻辑上的主语必须与句子的主语一致。如果主从句的主语不一致，在取消掉从句变为-ing 或-ed形式时，要把从句的主语保留，其它部分和以前的改法一样。

例如：As it was hot, we went swimming.

→It being hot, we went swimming.

注意：在用分词短语作状语时，它也可以有自己独立的逻辑上的主语，这种结构称为独立主格结构。在很多的情况下它都表示一种伴随的动作或表示一种原因。例如：

1. If weather permits, I will go there.

→Weather permitting, I will go there.

2. After the shower was over, we continued to march.

→The shower being over, we continued to march.

3. Late that autumn, when his work was finished, he prepared to return to his institute.

→Late that autumn, his work finished, he prepared to return to his institute.

4. As so many comrades were absent, we decided to put the meeting off.

→So many comrades being absent, we decided to put the meeting off.

通过上面的例句我们可以看出，v-ing的一般式所表示的动作大都和句子中的谓语动词所表示的动作同时发生或动作正在进行。v -ing的完成式表示的动作在句子中谓语动词所表示的动作或状态之前发生。这时它在句子中多作状语，表示时间和原因。表示时间时，常放于句首;表示原因时，常放在句末或句首。

现在分词和过去分词一样，也可以作状语，很多都说明动作发生的背景或情况;所不同的是现在分词所表示的是主动而过去分词表示的是被动。

综上所述，非谓语动词做状语的用法可以分为4类：

1. v-ed表被动，更多的情况下也表示动作的完成，作状语时更是如此;

2. v-ing表主动，其一般式所表示的动作大都和句子的谓语动词所表示的动作同时发生或v-ing所表示的动作正在进行，有时还可以表示结果。

3. v-ing的完成式表示的动作在句中谓语动词所表示的动作或状态之前发生。

4. v-ing的被动完成式表示的动作在句中谓语动词所表示的动作或状态之前发生，并且是被动的。

总之，尽管非谓语动词的用法非常复杂，但归纳一下，其实很简单，掌握动作的主动与被动，先分清是v -ing 还是v -ed;然后看它所表示的动作和句子主语的动作时间上的关系来决定是用v -ing的一般式还是用v -ing的完成式，还是用其被动完成形式。

一、非谓语动词与从句的相互关系

(一)不定式和分词作定语相当于定语从句

不定式通常位于被修饰名词后。与该名词构成逻辑上的动宾关系。如果不定式与所修饰名词在意思上是被动且逻辑上的主语不出现时，要用不定式的被动式，与所修饰名词构成逻辑上的主谓关系。分词作定语时，单个分词置于名词之前，分词短语置于名词之后，与名词构成主谓关系或被动主谓关系。定语从句和不定式、分词作定语只是两种不同的表达方式，本质是相同的。【不定式作定语时，放在被修饰词之后，表将要发生的事；动名词放在被修饰的词之前，表用途；现在分词作定语，放在被修饰词后，含有进行和主动的意思。可认为单个放前，短语放后】

例如：I have many letters to type．(动宾关系)

→I have many letters which I should type．

I have many letters to be typed．(被动主谓关系)

→I have many letters which are to be typed by other．

The standing people shouted at the dog =The people who is standing shouted at the dog ．(主谓关系)

(二)不定式和分词作状语相当于状语从句

1．不定式多作目的状语和结果状语．故可以转化为相应的目的状语从句和结果状语从句。

例如：Mother got up early to catch the early bus．(目的状语）

→Mother got up so early as to(in order to)catch the early bus．

→Mother got up early so that(in order that)she might catch the early bus．

【注意】so as to和so that不可放在句首。

She is too young to join the army．(结果状语)

She is so young that she cannot join the army．

2．分词作状语可以表示时间、原因、条件、方式和让步等，相当于相应状语的从句。如果分词的逻辑主语与主句主语一致，则用现在分词；如果分词的逻辑主语与主句是被动关系且主语一致时，则用过去分词。分词作状语时，如果其带有逻辑上的主语，称为分词的独立主格结构。分词的逻辑主语与句子的主语无语法联系。

例如：Seeing those pictures．he couldn't help thinking of the unforgettable days in New York．(时间状语)