(1)as...as可以用在肯定句中，表示“像...一样”，后面的形容词或者副词要用原级：

She can run as fast as a deer. 她能跑的像鹿一样快。

They work as hard as they do. 他们工作像你一样努力。

(2)as...as也可以用在否定句中，此时和so...as都可以用：
I don't go there as much as I used.我现在到那里不像过去那么多了。
I didn't do as(so) well as I should.我做的不如我应做的那么好。

（3）)as...as用在句中表示程度：
I don't speak half as (so) well as you.我讲得不及你一半好。
She can read twice as fast as he does.她的阅读速度比他快一倍。

注：表示与……一样的时候，用the same as或者same as ,不可用as same as