近期环球教育天津学校杨卓睿教师在进行GMAT考试的备课工作，在做逻辑题（Critical Reasoning）时遇到了一些有意思的题目，在这里和读者分享一下解题的经验和思路。

　　其中一题是 GMAT Verbal Review 2nd Edition 第148页的78题。题干是这样说的：

　　Which of the following most logically completes the passage?

　　The figures in portraits by the Spanish painter El Greco (1541-1614) are systematically elongated. In El Greco's time, the intentional distortion of human figures was unprecedented in European painting. Consequently, some critics have suggested that El Greco had an astigmatism, a type of visual impairment, that resulted in people appearing to him in the distorted way that is characteristic of his paintings. However, this suggestion cannot be the explanation, because_____.

　　(A)several twentieth-century artists have consciously adopted from El Greco's paintings the systematic elongation of the human form

　　(B)some people do have elongated bodies somewhat like those depicted in El Greco's portraits

　　(C)if El Greco had an astigmatism, then, relative to how people looked to him, the elongated figures in his paintings would have appeared to him to be distorted

　　(D)even if El Greco had an astigmatism, there would have been no correction for it available in the period in which he lived

　　(E)there were non-European artists, even in El Greco's time, who included in their works human figures that were intentionally distorted

　　这道题在OG中出现的位置靠后一些，属于难度较大的题目，但是可以通过排除"新概念"的方法选出正确选项。"新概念"是指题目的选项中引入了题干中不曾提及的新的概念，一般是以名词或名词短语的形式出现。

　　GMAT 考试逻辑题的答题思路是根据已知信息推测已知信息之间的关系，而不是根据已知推未知。例如，如果题目中给出了"A喝水"这个已知信息，考生要做的是分析"A"和"喝水"这两个主要对象之间的逻辑关系，而不能从"A喝水"这件事想象出"A可能口渴"这个背景。如果"A可能口渴"作为选项出现，"口渴"就是未曾提及的新的概念。

　　对于这道题目来说，题干中并没有提及 A, B, D, E 四个选项中分别出现的"twentieth-century artists, some people, correction, non-European artists"这四个概念。换句话说，这四个新的概念不属于题干中所讨论的信息。这属于"引入新概念"的错误。排除这四个选项即可选出正确答案 C。

　　本题题干先描述了一个故事，然后引述了一些人对这个故事的解释，最后让考生找到驳斥这个解释的理由。故事是一个16世纪的西班牙画家所画的肖像画中的人物全是拉伸的（elongated）。这种画法在欧洲是没有先例的。

　　因此有人认为这位画家有散光，看到的人物都是拉伸的，因此也这样画出来。C 选项的驳斥说如果这位画家有散光的话，日常的人们在他眼里以一种扭曲的形象出现。如果他知道自己有散光的话，会矫正自己所画的人物使其趋近正常。暗示有散光的画家不可能画出身长拉伸的人物。

　　"引入新概念"是 GMAT 逻辑题错误选项的一种常见情况。规避这类选项能够帮助考生排除错误选项，甚至直接选出正确选项。