在每一次的SAT考试里，有关语法部分针对逻辑主语判断的考察基本上已经占据了三分之一，这算是一个相当大的比例。尽管此方面大部分题目类型都很浅显易懂，有的更甚一步能够找出答案，但考官若换一个出题思路，而不加以提示，大家是会陷进其套。所以在此要告诉大家的是警惕SAT语法中的逻辑主语问题。本文环球教育小编为了帮助SAT考生快速的理解这个问题同时掌握解决办法，特别整理了SAT语法的逻辑主语两大考点。

　　SAT语法的逻辑主语考点一、逻辑主语问题的常见有下面几种形式：

　　1. 句子以现在分词开始

　　例如，Lacking good instruction, my mistakes in creating a graph to illustrate historical trends were numerous.( 句子以现在分词lacking开始)

　　my mistakes in creating a graph to illustrate historical trends were numerous

　　I made numerous mistakes in creating a graph to illustrate historical trends

　　there were numerous mistakes in the graph I created to illustrate historical trends

　　I created a graph to illustrate historical trends with numerous mistakes

　　The graph I made for illustrating historical trends had numerous mistakes

　　2. 句子以过去分词开始

　　例如，Carried by the strong, dry winds of the stratosphere, the 1980 eruption of Mount Saint Helens caused dust thatcrossed the United States in three days and circled the globe in two weeks. (句子以过去分词carried开始)

　　the 1980 eruption of Mount Saint Helens caused dust that

　　Mount Saint Helens’ eruption in 1980 caused dust that

　　dust from the 1980 eruption of Mount Saint Helens

　　dust from the 1980 eruption of Mount Saint Helens that

　　there was dust from the 1980 eruption of Mount Saint Helens and it

　　3. 句子以介词加分词开始

　　例如，By simply entering an internet website or calling a toll-free number, a catalog order can be placedfor almost anything from cheesecakes to fully equipped desktop computers. (句子以介词by加分词enteringor calling开始)

　　a catalog order can be placed

　　by placing a catalog order

　　they will place your catalog order

　　you can place a catalog order

　　your catalog order can be placed

　　解读SAT语法中的逻辑主语考点图2

　　SAT语法的逻辑主语考点二、修改方法

　　从语法上来说，若句子开始属于分词结构，如此它的逻辑主语一定是整个句子的主语。在修改句子题里却通常是相反的，相当于是句子的主语不是分词结构的逻辑主语。修改的技巧是“一步必杀”法：把句子的主语替换成为分词结构的逻辑主语(一般藏在句子中)。正确答案通常就是以分词结构的逻辑主语为句子主语的选项。根据“一步必杀”法，上述句子修改如下。

　　1. Lacking good instruction, my mistakes in creating a graph to illustrate historical trends were numerous.

　　my mistakes in creating a graph to illustrate historical trends were numerous

　　I made numerous mistakes in creating a graph to illustrate historical trends

　　there were numerous mistakes in the graph I created to illustrate historical trends

　　I created a graph to illustrate historical trends with numerous mistakes

　　The graph I made for illustrating historical trends had numerous mistakes

　　如今分词lacking的逻辑主语，相当于是整个句子的主语应该是“I”，但事实上却是“my mistakes”。修改时只需要把句子的主语改成是“I”即可。符合此要求的有和2个选项，当中选项将numerous mistakes放错了位置，这样让整个句子意思荒谬。因此为正确答案。这也告诉考生，正确答案只要改正原句的主要错误就可以了，而无须做太多额外的修改，因为与原句相比，这么做将使改后的句子变得面目全非。

　　2. Carried by the strong, dry winds of the stratosphere, the 1980 eruption of Mount Saint Helens caused dust thatcrossed the United States in three days and circled the globe in two weeks. (句子以过去分词carried开始)

　　the 1980 eruption of Mount Saint Helens caused dust that

　　Mount Saint Helens’ eruption in 1980 caused dust that

　　dust from the 1980 eruption of Mount Saint Helens

　　dust from the 1980 eruption of Mount Saint Helens that

　　there was dust from the 1980 eruption of Mount Saint Helens and it

　　过去分词carried的逻辑主语，相当于整个句子的主语算得上是“dust”(dust 被winds吹走)，而事实上却是“eruption”。修改时只要求把句子的主语改成是“dust”即可。符合这个要求的有与两个选项，其中选项保留了原句的that，使得that之后的crossed成了that引导的从句的谓语，也使得整个句子没有谓语，因此为干扰选项， 为正确答案。

　　通过以上分析的SAT语法的逻辑主语两大考点，希望大家可以针对文中介绍的方法进行有针对性的备考，预祝大家在SAT考试中取得好成绩!