as这个小小的词经常让学生困扰不已，因为它的使用非常灵活，既然这么灵活，我们学生更应该记住GMAT会考到的形式是什么，只需要记住GMAT会涉及到的情况即可。接下来我们用官方题目的答案句子来剖析下as在gmat中的常见用法：
1）做介词
表达-作为，当做的意思：
a）单独用
Ryūnosuke Akutagawa's knowledge of the literatures of Europe, China, and Japan was instrumental in his development as a writer.
As an actress and, more importantly, as a teacher of acting, Stella Adler was one of the most influential artists in the American theater, training several generations of actors whose ranks included.......
b）短语中的as（最常见的 such as ）
Many kitchens today are equipped with high-speed electrical gadgets, such as blenders and food processors, capable of inflicting injuries as serious as those caused by an industrial wood-planing machine.
（as....as..结构中，第一个as是副词，第二个as可以是介词也可以是连词，取决于后面接名词还是接句子）
In her presentation, the head of the Better Business Bureau emphasized that companies shouldthink of the cost of conventions and other similar gatherings not as an expense, but as an investment in networking that will pay dividends.
2）做连词
a）比较结构中表达比较，接句子
According to a recent poll, owning and living in a freestanding house on its own land is still a goal of a majority of young adults，as it was of earlier generations.
To meet the rapidly rising market demand for fish and seafood, suppliers are growing fish twice as fast as they grow naturally, cutting their feed allotment by nearly half and raising them on special diets.
（as表达比较有时候会省略，以至于后面只接了一个介词短语的成分。
X caused a worldwide sensation in no other sighting as [X caused ...] in its return.）
b）相当于 when while, 当....随着...
One legacy of Madison Avenue's recent campaign to appeal to people fifty years old and over is the realization that as people ages, their concerns change as well.
c)as做连词还可以表达，让步，原因 等，但是GMAT这种情况出现不多。
3）做副词☆
表达正如...和...无不同
as...as结构中 第一个as
The first oversight board's philosophy and its actions are as influential on the industry now as they were revolutionary during the board's teure.
4）做关系代词
as可以做关系代词引导限定或者非限定 定语从句（就像that/which）
He smokes as expensive a cigarette as he can afford.
He is late, as is often the case.
习惯表达： as is known to all/ as seen from the table/ as is often said /as compared with...（这个经常出现在gmat中）
