在考研英语中，最让人闹心的便是长难句，但只要找出主干、理清成分也没有那么难以对付。相反，有一些小词，用法繁多，在不同句子中需要辨别出真正的意思就没那么简单了，今天文都网校考研英语老师就as词性的相关用法给大家进行梳理。

　　As作介词

　　从词性来看，as主要有介词、连词、关系词。当as作为介词时，往往与动词搭配，形式为...as...,这时动词就不要使用本意，而是统一翻译为将A视为B；把A看成B,在考研英语中出现的动词总结如下：see/view/regard/consider/identify/define/classify/interpret/dismiss/elect/accept/think of A as B。除了这些简单的词语外，当宾语A复杂时会后置于B，形式如下: v. as B A。我们来看一句话On the other hand he did not accept as well founded the charge made by some of his critics that while he was a good observer he had no power of reasoning.动词是accept，介词是as，as后直接跟的宾语B（形容词）,A由于复杂后置到了B后，是the charge,后跟一系列的定语-made by some of his critics以及同位语-while he was a good observer he had no power of reasoning，这句话是说另一方面，他认为一些批评者的指控没有根据，指控内容是说虽然他是个好的观察者，但他没有推理能力。

　　As当连词

　　当as作为连词时，可以表时间：随着....../当......时候（一般位于句首）。例句如下：As funding for science has declined, scientists have attacked "anti-science" in several books.随着用于科学的资金减少，科学家在一些书中攻击"反科学"论调。可以表原因：既然、由于=since。例句如下：We are obliged to them because some of these languages have since vanished, as the peoples who spoke them died out or became assimilated and lost their native languages.我们感激他们，是因为一些语言自此以后消失了，消失是由于这些语言使用者已经死去或者被同化，进而失去了他们本族语言。可以表让步：尽管、虽然，（as一定不能位于句首，位于句中第二个词）。例句如下：

　　In addition, difficult as it is to believe, there are desert fish which can survive through years of drought in the form of inactive eggs.另外，尽管很难相信，确实存在沙漠鱼，这些鱼以不活跃卵的形式在干旱中存活数年。可以表比较，as...as + 词/句子：和...一样、像...一样；not so......as + 词/句子：和...不一样、不像...那样；not so much...as...:与其说...不如说...。可以表方式，等于in the way that,按照、正如。

　　As作关系词

　　As作为关系词时，引导限定性定语从句：先行词前有such/the same；非限定性定语从句：修饰整个句子，比如As is known to all, ...；..., as is often the case；...,as you know,...。

　　以上是关于as的词性及用法梳理，接下来会在具体的例子中给大家进行讲解，以加强理解。希望大家能够通过这篇文章，把as的用法进一步巩固，祝大家复习愉快、考研顺利！