GMAT逻辑题型备考：区分前提和结论

正确区分前提的结论是GMAT逻辑题的基础能力，也是正确选对答案的基础。所有的传统问法GMAT考题的文章部分均需要区分前提和结论。

先谈谈前提和结论的定义（划重点）。

前提：最直接能推理得出结论的句子。

结论：作者最终通过推理得出的观点句。

解题时，要先找准结论，后基于结论找前提。找结论的方法主要有如下两种：

1. 结论信号词

在很多GMAT批判性推理的考题中，结论的前面会出现一个信号词。当出现这类信号词时，身后必然出现该推理文段的结论。这类信号词包括：therefore, consequently, clearly, thus等等。下文例题中用了结论信号词 therefore：

The country of Baurisia has, until now, been self-sufficient in both grain and meat. However, with growing prosperity, Baurisia has come a steadily increasing per capi-ta consumption of meat, and it takes several pounds of grain to produce one pound of meat. Therefore, since per capita income in Baurisia is almost certain to rise fur-ther but increases in domestic grain production are highly unlikely, Baurisia is soon likely to become an importer of grain.

Therefore之后为结论句部分(虽然最后的小半句“Baurisia is soon likely to become an importer of grain”才是真正的结论句，但是找到therefore，也就基本找到结论句了)。

2. 被支持的句子

有些GMAT考题中没有结论信号词，抑或是我们人为地将例题中的therefore去掉，例如：

The country of Baurisia has, until now, been self-sufficient in both grain and meat. However, with growing prosperity, Baurisia has come a steadily increasing per capi-ta consumption of meat, and it takes several pounds of grain to produce one pound of meat. Since per capita income in Baurisia is almost certain to rise further but in-creases in domestic grain production are highly unlikely, Baurisia is soon likely to become an importer of grain.

进行如此操作后，结论句依然为不变。由此可知，信号词本身并不影响我们对于结论句的选取。实际上，若题目中没有结论信号词，我们就需要从语义上判断结论。在整个推理文段中，一定有且仅有一句话是被其他句子所支持的，而其他的句子都是为这句话服务的。这个被支持的句子就是“结论句”。在例题中，显然整个文章都在论证“Baurisia很快就会变成谷物进口商”，因此它就是结论句。

从经验上来讲，很多题目的结论句都出现在推理文段的末尾。因此，请对末尾的句子更加留心。

并非除掉结论外的所有句子都是前提，大部分句子只是背景而已。例如上文，最直接能推理得出结论的句子为：

Since per capita income in Baurisia is almost certain to rise further but in-creases in domestic grain production are highly unlikely

这句话是前提句，其余的句子皆为背景。

为了准确找到前提，可以用设问法。找到结论后，问自己，文章凭什么有这个结论？文章中哪句话最能回答清楚这个问题，哪句话就是前提。

例如，问：凭什么说“Baurisia会变成谷物进口商”呀？

自己回答：因为收入会增加且谷物产量不会增加。