托福阅读：如何找准句子主干

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托福要想拿到高分，阅读是必须拿高分的。然而，很多学生词汇背了很多，阅读也做了很多，成绩提升却不明显。长难句分析一直是很多学生薄弱的地方，那么，我分享一些分析长难句的方法。

分析长难句的核心在于抓住主干，分析修饰成分。

Part One

第一， 什么是句子主干？

答案是，五大基本句型。

主语+谓语（不及物动词）           Legends abound.

主语+谓语+宾语                    I ate an apple.

主语+表语+系动词                  She is sleeping.

主语+谓语+直接宾语+间接宾语       My father bought me a car.

主语+谓语+宾语+宾语补语           I found this computer useful.

不管多么复杂的句子，句子的主干都跑不了这五种基本句型。但是仍有些需要注意的地方。

1、 找主语

大部分情况下，主语都是位于句首的第一个名词、代词、数词、动名词或者动词不定式。这儿指出两个容易犯错的地方。

1） 代词也可以做主语

Another, advanced in the twentieth century, suggests that humans have a gift for fantasy, through which they seek to reshape reality into more satisfying forms than those encountered in daily life.

这是个代词做主语的情况，且another 后省略了名词，它就是句子的主语。

2） 句首出现介词短语

倒装 Among the main factors are Teotihuacán’s geographic location on a natural trade route to the south and east of the Valley of Mexico, the obsidian resources in the Teotihuacán Valley itself, and the valley’s potential for extensive irrigation.

这是介词短语位于句首倒装的情况，句子主干是Location，the obsidian resources and the valley’s potential are among the main factors.

基本结构是 A is among B. 介词短语做句子成分的情况，是在主系表结构中做表语。

做修饰成分  In these shops differences of rank were blurred.

在这个句子中，出现了介词in，句子又是正常语序，有些学生会误把shops 当做主语，其实介词+名词构成介词短语大部分都是起修饰作用，在这个句子中是限定发生的地方。

2、 找谓语动词

这个对很多学生来说，都是个大难点。

1）、非谓语动词VS谓语动词

顾名思义，非谓语动词就是不可以做谓语的动词，有三大类：动词不定式（to do）、现在分词(-ing)和过去分词（-ed）。

现在分词用法 

现在分词（短语）后置，表主动

eg. The man holding a magazine is my father.

现在分词放在名词前，表主动、正在进行的

eg. China is a developing country.

过去分词用法

过去分词（短语）后置，表被动

The job finished by this group is a marvelous.

过去分词前置，表完成的动作，无被动含义

a sank ship沉船   a fallen leave 落在地上的叶子  a falling leave正在飘落的叶子

如何区分过去分词是做谓语动词还是做修饰成分？

a、 看时态，如果是一个过去分词的动词一个现在时态的动词，则一般过去分词修饰，因为现在时态的动词不可能做修饰成分

The environmental changes associated with this transition are not fully understood, but people living closest to the San Juan Mountains, to the northeast of Mesa Verde, were affected first.

b、 过去时态，一个be动词的过去式，一个其他动词的过去式，则动词是be动词的过去式

c、过去时态，都是实义动词的过去式，根据句子意思和搭配来判定

2）、主语和谓语被插入语隔开

This “atmospheric engine”, invented by Thomas Savery and vastly improved by his partner, Thomas Newcomen, embodied revolutionary principles, but it was so slow and wasteful that it could not be employed outside the coal mines for which it

had been designed.

主干：This “atmospheric engine” embodied revolutionary principles.

The central state, though often very rich and very populous, was intrinsically fragile.

3）、在从句修饰主语或者主语后的其他修饰成分太长的情况下，误把从句中的动词当做谓语动词。

At one time, the animals present in these fossil beds were assigned to various modern animal group.

3、 找宾语

1）、宾语太长后置，导致找不到宾语

But the myths that have grown up around the rites may continue as part of the group’s oral tradition and may even come to be acted out under conditions divorced from these rites.

2)、从句做宾语

The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing.

3）、插入语把谓语和宾语隔开

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