在GMAT阅读中，复杂修饰成分和插入语的混合使用通常对考生顺利解题造成障碍，较多出现插入语是英语与汉语的一个显着区别，在遇见有插入语的句子时，考生思路很容易被打断，阅读速度降低，干扰对句意的理解。GMAT阅读中比较常见的插入语有以下四种形式：
1、as引导的短语或句子作插入语
例句：The factors favoring unionization drives seem to have been either the presence of large numbers of workers, as in New York City,to make it worth the effort, or the concentration of small numbers in one or two locations, such as a hospital, to make it relatively easy.
解析：这个句子中出现的两处插入语都表示举例，插入语后面接不定式表目的。本句中的as后接的是介词短语，插入语比较短，有时候as 会引导一个句子，用来分散考生注意力。我们先把两处插入语省略掉，句子变成The factors favoring unionization drives seem to have been either the presence of large numbers of workers to make it worth the effort, or the concentration of small numbers in one or two locations to make it relatively easy.这样以来，either or 表示的并列结构就很清晰了。
2、介词短语作插入语
例句：Now Congress, in apparent agreement, has required by law that businesses awarded federal contracts of more than $500,000 do their best to find minority subcontractors and record their efforts to do so on forms filed with the government.
解析：本句的插入语出现在主语之后，把主语和谓语分隔开来，这种插入语其实也可以和其他成分连接在一起，用插入语的形式表现出来反而更分明一些。虽然插入语会使得考生思路被打断，分散注意力，但在这种情况下它能成为一种信号，告诉考生这里可以暂时不读，对句子结构的理解不造成任何影响。本句的难点在于过去分词作定语，例如business awarded federal contracts和forms filed with the government.
3、非限制性定语从句相当于插入语的功能
例句：How such large creatures, which weighed in some cases as much as a piloted hang-glider and had wingspans from 8 to 12 meters, solved the problems of powered flight, and exactly what these creatures were-reptiles or birds are among the questions scientists have puzzled over.
解析：非限制性定语从句与限制性定语从句的一个区别在于非限制性定语从句中和先行词之间只有比较松散的关系，出现在句中也是用逗号隔开，具有插入语的功能。 我们先将插入部分略过不读，很容易发现这是一个疑问句。特殊疑问词为how much和what，从本句还能看出插入语的处理是非常灵活的，句中的reptiles or birds也可以看成插入成分。非限制性定语从句作插入语比较特殊的是弄清句子结构之后再回头看时，要与先行词紧密对应。但是这只限于非限制性定语从句出现在句中的情况下，如果出现在句尾，就不能当作插入语。
4、复杂名词结构作插入语
例句：Increasingly, historians are blaming diseases imported from the Old World for the staggering disparity between the indigenous population of America in 1492—new estimates of which soar as high as 100 million, or approximately one-sixth of the human race at that time—and the few million full-blooded Native Americans alive at the end of the nineteenth century.
解析：如果句中插入名词一般会视为同位语对待，但是同位语不会设置得如此复杂，而且起到进一步解释说明的作用，本句的插入语不同于一般用两个逗号隔开的情况，而是用两个小横线进行提示，作用相同。先把这部分复杂名词去掉，句子结构顿时豁然开朗，无非就是between…and的结构形式。这种情况下名词的出现也经常使用从句和多种修饰成分，所谓的“句子套句子”。这个句子中的插入语首先是or 连接的并列结构，而两个结构又不是平行的，前半句使用从句，后半句用of的结构，实际上不过就是用这个复杂成分来表示一个大致的数字。
构成插入语的成分可以是单词、短语或是句子，用来补充含义或作出一些解释，把插入语从原文中抽取出来，句子结构不会发生变化。如果插入语过长，我们可以先略过这部分，等从整体上把握句意之后再回头看插入部分的内容。总的来说，GMAT阅读中不会出现象
(编辑：suyan)