我们知道逻辑语义在整个GMAT考试中都是要的核心考点，所以在GMAT SC部分中，我们不能觉得SC是在考语法而忽略掉这个考点，并且是要在掌握其他考点的前提之下，把逻辑语义融入到每一道题里去，不管是高分题还是低分题，一个句子要表达明确，都是要逻辑合理的，那么逻辑语义会怎么考，经常出错的问题在哪里呢？
　　一、GMAT SC逻辑语义题常见错误：
　　1、句子结构发生变化：
　　A、句子重心改变
　　B、句子主次关系变化（主句和修饰之间的主次关系）
　　C、修饰部分之间（定语变状语等等）
　　2、句子关系错误：连词错误
　　3、词语搭配错误，不符合常识
　　二、GMAT句子改错中常见的思路：
　　1、原句主干与修饰部分的关系是合理的，选项改变主干与修饰的主次关系则错。
　　2、修饰部分本身错，比如要修饰整句话，但是用了which。
　　3、原句的介词短语，副词所在位置体现的逻辑语义正确，选项中如果位置改变会导致语义变化。
　　4、原句的句子连词所表达的语义正确，如and/but/or，不要随意改变。
　　5、原句如果不存在连词，逻辑合理，选项中增加连词的要警惕。
　　6、选项当中如果改变了主语，很可能改变句子语义。
　　7、语义重复则错误。
　　8、不符合常识。
　　三．通过例题了解GMAT逻辑语义考点
　　1、Each year companies in the United States could save as much as $58 billion annually by preventing illness among employees and gain as much as $200 billion through improving performance of workers if they simply provided offices with cleaner air.
　　A、annually by preventing illness among employees and gain as much as $200 billion through improving performance of workers if they simply provided
　　B、annually if they prevented employee illness and gain as much as $200 billion through worker performance improved by simply providing
　　C、annually in employee illness prevention and gain as much as $200 billion through worker performance improved by simply providing
　　D、in employee illness prevention and gain as much as $200 billion through improving performance of workers if they simply provided
　　E、by preventing illness among employees and gain as much as $200 billion through improved worker performance if they simply provided
　　解析：考点：逻辑语义 平行
　　ABC选项，annully与each year语义重复，排除。
　　D选项，and前后不平行，且从语义上来看，句首要表达的是“通过”的语义，应用介词BY。
　　by preventing illness和through improved worker performance功能平行。
　　2．In 1945, after a career as First Lady in which she shattered expectations more audaciously than either Abigail Adams or Dolly Madison ever had been, Eleanor Roosevelt was appointed a delegate to the United Nations General Assembly by President Harry S Truman.
　　A、more audaciously than either Abigail Adams or Dolly Madison ever had been, Eleanor Roosevelt was appointed a delegate to the United Nations General Assembly by President Harry S Truman
　　B、more audaciously than either Abigail Adams or Dolly Madison, President Harry S Truman had Eleanor Roosevelt appointed to be a delegate to the United Nations General Assembly
　　C、with an audacity never matched in the case of Abigail Adams or Dolly Madison, President Harry S Truman had Eleanor Roosevelt appointed as a delegate to the United Nations General Assembly
　　D、with an audacity never matched by Abigail Adams or Dolly Madison, Eleanor Roosevelt was appointed a delegate to the United Nations General Assembly by President Harry S Truman
　　E、with an audacity never matched either in the case of Abigail Adams or of Dolly Madison's, Eleanor Roosevelt was appointed to be a delegate to the United Nations General Assembly by President Harry S Truman
　　解析：考点：比较 逻辑语义 动词形式 平行 修饰
　　介词短语after a career as First Lady放句首作状语，和主句主语存在逻辑关系，after a career as first lady的人应该是Eleanor Roosevelt，所以必须是ER作主语；
　　A than前后比较，比较的前面出现的动词是shattered，than后应该用did或had done来代替，而不是had been；
　　B 主句主语是president，修饰关系发生改变；
　　C 同B
　　D 正确
　　E either in the case of Abigail Adams or of Dolly Madison's结构不平行；