作者：本质教育 李泽宇

Official Guide是每一个考GMAT的学生必须具备的书籍。里面的每一道题目最好做2遍以上（尤其是错题，一定要好好分析体会）。很多同学告诉我，OG的答案不够清楚。事实上，OG的有些讲解试图绕开一些需要补充的知识，例如什么是溯因推理，因此往往显得不够清晰。因此，我想我每天抽出一些时间，写一道OG的题目，帮助大家学习。

1. According to some critics, watching television not only undermines one's ability to think
critically but also impairs one's overall ability to perceive.
A. not only undermines one's ability to think critically but also impairs one's
B. not only undermines one's ability of critical thinking but also impairs the
C. undermines not only one's ability to think critically but also impairs one's
D. undermines not only one's ability of critical thinking but also impairs the
E. undermines one's ability not only to think critically but also impairs one's

这是一道简单题：
not only A but also B
是平行对称结构（parallelism），要求A,B尽可能的对称（但要注意有例外，例如现在分词doing和过去分词done是可以对称的，这个后面遇到难题再说）
这句话我首先读underlying部分，没有发现什么明显的问题，接着我比较A,B两个选项：
记住：Mistake must lie in the differences (although not all differences are mistakes)
差异的地方一个就是：A. ability to do sth vs. B. ability of sth

Idiom:
ability (of sb) to do sth
ability for doing sth/ability of sth/ability for sb to do sth -> WRONG

这个没办法，必须要背下来的。

然后浏览剩下的选项，那么D也可以排除了
接下来的C很明显是平行对称的问题: not only 后面跟的是名词短语one’s ability to think...而but also后面却是动词impairs，因此错误。快速浏览，同样的错误排除D,E

答案：A