在SAT考试中，语法题目的常见错误类型是逻辑主语错误，即句子的主语不是分词结构的逻辑主语。修改这种错误的方法很简单，只要用隐藏在句子中的逻辑主语替换掉句子原来的主语即可。下面，跟着环球教育SAT考试来看四道典型的例题!

1. 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

现在分词lacking的逻辑主语，即整个句子的主语应该是I，而原句中却是my mistakes。修改时只需要将句子的主语改为I就可以了。符合这个要求的有(B)与(D)两个选项，其中(D)选项将numerous mistakes放错了位置，使得整个句子意思荒谬。因此(B)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，否则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 that crossed the United States in three days and circled the globe in two weeks.