【改错精选120练】GMAT官方讲解SC难点实例分析（九十七练）

GMAT句子改错题(sentence correction)，是整个GMAT考试中对考生英语语法能力考查要求最高的题型，也往往是中国学生最为头疼的一类题目。没有扎实的语法基础和一定的逻辑分析能力，想要做好句子改错题难度极高。如何提升GMAT句子改错题的解题能力?下面小编就为大家整理了一些经典例题，结合实例分析为大家讲解GMAT句子改错题的解题思路和方法技巧。

实例题目：

Some anthropologists believe that the genetic homogeneity evident in the world’s people is the result of a “population bottleneck” – at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.

(A) at some time in the past our ancestors suffered an event, greatly reducing their numbers

(B) that at some time in the past our ancestors suffered an event that greatly reduced their numbers

(C) that some time in the past our ancestors suffered an event so that their numbers were greatly reduced,

(D) some time in the past our ancestors suffered an event from which their numbers were greatly reduced

(E) some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,

选项分析：

(A)at some time in the past our ancestors suffered an event, greatly reducing their numbers

【错误】 修饰关系：“，greatly reducing their numbers”作结果修饰，表达“our ancestors suffered an event”的结果，而无法如(B)中那样用“that greatly reduced their numbers”修饰“an event”，于是本选项表意为“过去人类祖先遭遇了(泛指的，不知道是什么的)一件事，结果(这一遭遇)减少了他们的数量……”，这种表意逊于(B)的表意——“人类祖先在过去某时遭遇了一件减少他们数量因而减少我们基因多样性的事”。

(B)that at some time in the past our ancestors suffered an event that greatly reduced their numbers

【正确】 “that”引导的从句“at some time in the past our ancestors suffered an event”是对从句“that the genetic homogeneity evident in the world's people is the result of a‘population bottleneck’”的解释说明。“that”使得这种“从句解释从句”的对应解释关系更加明确。“that greatly reduced their numbers”是“event”的定语从句，揭示了“事件”的具体内容。

【大意】 一些人类学家相信世界各族人之间明显的基因同质性是“人口瓶颈”的结果——曾经一个时候我们的祖先遭受了一个极大地减少其数量，因此减少我们人类的基因多样性的事件。

(C)that some time in the past our ancestors suffered an event so that their numbers were greatly reduced,

【错误】 固定搭配：“so that”不同于“so(such)……that……”前者连接的是主句的目的，而后者连接的才是主句的结果，因此本选项误用搭配“so that”。

(D)some time in the past our ancestors suffered an event from which their numbers were greatly reduced

【错误】 定语从句“from which their numbers were greatly reduced”还原成正常语序后应为“their numbers were greatly reduced from such event”，其本意想表达“他们(古人类)的数量因为这一事件被大幅降低”，但“from such event”也就是原先的“from which”结构无法表达用于表达原因。

(E)some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,

【错误】 固定搭配：“so as to”不同于“so(such)……as to……”前者连接的是主句的目的，而后者连接的才是主句的结果，因此本选项误用搭配“so as to”。

解题思路：

根据“so that”和“so as to”两个固定搭配的用法，立即排除(C)、(E)。

比较(A)、(B)、(D)选项，(B)选项用定语从句“that greatly reduced their numbers”修饰并解释“an event”，且用破折号加“that at some time in the past our ancestors suffered an event”修饰并解释与之平行的“that the genetic homogeneity evident in the world's people is the result of a ‘population bottleneck’”，表意最为合理。因此选择(B)。