大家都知道，在SC板块对大家的考察里，语法不是唯一的重点，而什么才是SC的精髓呢？对，是逻辑语义！逻辑贯穿我们整个GMAT考试,当然是重点,也是我们的一个核心思维,那今天雷哥GMAT就带着大家一起来解读一下SC里的逻辑语义,到底需要注意哪些方面,帮助大家梳理一下！

首先,大家需要明确一点,那就是逻辑=主干+修饰,大家在做SC题目时千万那不要钻进语法点的牛角尖里死抠,要从整个句子想表达的真正意思出发,才可以拿下SC. 逻辑=主干+修饰”,这个公式其实已经说明了,所有提出来的主干和修饰,都视为什么服务,都是为逻辑服务的. 

那逻辑考点大家要明确的第一点,就是先要学会如何去识别逻辑考点，它会怎样考怎样出.即以下4种方法:

知道了考点的识别，其次就是要遵循：如果原句逻辑合理，轻易不改变主干逻辑意思，如果逻辑不合理，选出原句想表达的逻辑意思这样的一个原则。

然后，给大家分享3点逻辑语义里常见的错误，帮助大家更好的理解：

① 句子主干发生变化（重心、主次、修饰）

② 句子关系错误（fanboys的变化）

③ 词的搭配（逻辑上）错误

说了那么多，不如实战来的具体，接下来给大家分析即到逻辑语义相关的题目，看看都有哪些逻辑上的错误。

第一题：

Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

A、Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are

B、Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are

C、Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are

D、Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,

E、Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,

这道题首先提出主干是Neuroscientists are now drawing solid conclusions，神经学家正在得出结论，跳过中间插入语：在过去二十年间已经得出了关于大脑和其从发育到成熟的发展这样的一个结论，然后插入语向前修饰神经学家，意为在过去二十年间已经得出了关于大脑和其从发育到成熟的发展这样的一个结论的神经学家，现在正在得出结论。主干修饰完整，逻辑语义通顺，保留，B选项主谓之间加入连词错误，C选项amassing 原本修饰的做了主干且有歧义用amassing当作谓语，错误，改编逻辑。DE则也是原本修饰成分having amassed变成主干have amassed，改变逻辑关系，就算改变后的逻辑通顺也不选，因为原句的逻辑已经正确，就不轻易改变了。

我们再来看一道题目：

New data from United States Forest Service ecologists show that for every dollar spent on controlled small-scale burning, forest thinning, and the training of fire-management personnel, it saves seven dollars that would not be spent on having to extinguish big fires.

A、that for every dollar spent on controlled small-scale burning, forest thinning, and the training of fire-management personnel, it saves seven dollars that would not be spent on having to extinguish

B、that for every dollar spent on controlled small-scale burning, forest thinning, and the training of fire-management personnel, seven dollars are saved that would have been spent on extinguishing

C、that for every dollar spent on controlled small-scale burning, forest thinning, and the training of fire-management personnel saves seven dollars on not having to extinguish

D、for every dollar spent on controlled small-scale burning, forest thinning, and the training of fire-management personnel, that it saves seven dollars on not having to extinguish

E、for every dollar spent on controlled small-scale burning, forest thinning, and the training of fire-management personnel, that seven dollars are saved that would not have been spent on extinguishing

这道题主干是New data show that，然后宾从that里介词for后面是介词短语，没有跟句子，是spent on sth , sth and sth都是后置定语修饰every dollar的，所以介词后面不是句子，正确。那逻辑点在哪呢？ACDE里均有否定词not,只有B选项里没有，那到底应该有not还是没not呢？我们来看逻辑，说新数据显示，显示啥呢？每花费在这些，这些和这些上的一美元，就节省了应该花还是不应该花在灭火上的7美元呢？也就是到底该不该有那个not？由逻辑语义可知，应该花儿没花，才叫saved,你都不应该花了，怎么叫省了呢？所以此题答案为B，当然除了这一点，A选项it指代不明，代词指代不明确，做主语，应变为被动，如正确选项B。C选项saves前面依然没有主语，排除，DE则可根据句法结构，that不修饰前面的personnel，不引导非限定从，排除DE。

由上述例子可知，同学们在遇到逻辑类题目的时候，一定首先要搞清楚句子想表达的真正正确的逻辑意思是什么，才好判断自己选出的选项是否正确，而能分辨出正确的逻辑语义又基于能准确的提出主干，看出修饰。所以这两者相辅相成。希望大家在做逻辑语义类的题目时能够有一个清晰的思维。