as是什么？？

简明英汉词典
as

adv.
同样地, 被看作, 象
prep.
当做
conj.
与...一样, 当...之时, 象, 因为 [域] American Samoa, 东萨摩亚
abbr.
[军] Air to Surface, 空对地

现代英汉综合大辞典
as

n.
(pl. asses )阿斯
古罗马铜币 古罗马重量单位

现代英汉词典
as 1

adv.
同样；相同
He runs fast, but I run just as fast.
他跑得快，但我跑得同样快。
被看作；被认为是
man as described by scientists
科学家所描述的人类
as 2

n.
阿斯（古罗马铜币）
【词性变化】
as
conj.
（用于比较）与…一样
He can run as fast as I can.
他能跑得和我一样快。
She works in the same building as my sister.
她和我的妹妹在同一大楼上班。
This is the same as it was before.
这个与以前一样。
诸如
such animals as cats and dogs
诸如猫、狗之类的动物
当；正值
He dropped the glass as he stood up.
他站起来时，把杯子摔了。
【词性变化】
as
pron.
正如，照
as you know
正如你知道的
就…而言
He's quite good,