逻辑主语的考点在SAT考试语法部分也是必考的一项，尤其在改进句子题（IS题型）中经常出现。逻辑主语考题在考试中的难度并不算大，并且非常容易将选项中的两到三个迅速排除，所以同学们只要把知识点掌握牢固，可以达到事半功倍的效果。
概述：
逻辑主语是非谓语动词动作的执行者或承受者；它们在逻辑上存在着主谓关系或动宾关系，却不能直接作非谓语动词的主语，因此叫逻辑主语。
例句：Quincy took Dan to Jack’s house for a visit, (A) never imagining(B) that ten years would pass (C) before seeing (D) Jack again. No error (E)
在SAT语法考试中，尤其是IS题型中通常的出现形式有：
a. 句子以分词开始（现在分词和过去分词）;
b. 介词加名词开始;
c. 连词加分词或者形容词开始。
考点聚焦：
（1）. 句子以现在分词开始
例句：Lacking good instruction, my mistakes in creating a graph to illustrate historical trends were numerous.
(A) my mistakes in creating a graph to illustrate historical trends were numerous
(B) I made numerous mistakes in creating a graph to illustrate historical trends
(C) there were numerous mistakes in the graph I created to illustrate historical trends
(D) I created a graph to illustrate historical trends with numerous mistakes
(E)The graph I made for illustrating historical trends had numerous mistakes
（2）. 句子以过去分词开始
例句：Carried by the strong, dry winds of the stratosphere, the 1980 eruption of Mount Saint Helens caused dust that crossed the United States in three days and circled the globe in two weeks.
(A) the 1980 eruption of Mount Saint Helens caused dust that
(B) Mount Saint Helens’ eruption in 1980 caused dust that
(C) dust from the 1980 eruption of Mount Saint Helens
(D) dust from the 1980 eruption of Mount Saint Helens that
(E) there was dust from the 1980 eruption of Mount Saint Helens and it
（3）. 句子以介词加动名词开始
例句：By simply entering an internet website or calling a toll-free number, a catalog order can be placed for almost anything from cheesecakes to fully equipped desktop computers.
(A) a catalog order can be placed
(B) by placing a catalog order
(C) they will place your catalog order
(D) you can place a catalog order
(E) your catalog order can be placed
（4）. 句子以连词加分词或形容词开始
例句：While driving down the road, the house with the large yard and small pond attracted the family’s attention
(A) the house with the large yard and small pond attracted the family’s attention
(B) the house having the large yard and a small pond attracted the attention of the family
(C) the house with the yard and small pond was attractive to the family’s attention
(D) the family’s attention was attracted by the house with the large yard and small pond
(E) the family was attracted to the house with the large yard and small pond
