(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
参考资料：http://zhidao.baidu.com/question/198100514.html

(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

一、“as(否定句中可用so)＋adj．／adv．＋as…”，其基本意思为“……和……一样”。但在实际应用中，此结构在www.souquanme.com不同的语境中含义差异较大。
1、表示不同人或物同一性质的比较，意为“……和……一样……"。
　　The tree is as tall as the building(is)．
　这棵树和那栋楼一样高。
　Michael is as bright as George(is)．
　迈克尔和乔治一样聪明。
　
2、表示同一个人或物不同性质的比较，意为“既……又……”
　Alice works as happily as(she)plays(happily)．
　艾丽丝愉快地工作，尽情地玩。
　Danny is not so wise as he is witty．
　丹尼为人风趣，但欠明智。
3、用于表示两个人或物不同性质的比较，表示程度相同或相当，意为“……而……”。
　　He was as handsome as his wife was beautiful．
　　他长得非常英俊，他的妻子也长得非常漂亮。
　　He was as experienced as his brother was green．
　　他经验丰富，而他兄弟却涉世未深。
　　
二、as…as结构的另一种形式是“as much／many＋名词＋as＋从句”。
　　Mary has written as many essays as her brother．
　玛丽写的文章篇数和她弟弟一样多。
　It is as much your fault as your wife’s．
　这既是你的过错，也是你妻子的过错。
　Henry is as much a hypocrite asJohn．
　亨利跟约翰一样是个伪君子。
三、若有修饰成分，如twice，three times，half，a quaer等，必须置于第一个as之前。
　You are not half as clever as you think you are．你可不像自己想象的那么聪明。
　She isn’t going out with a man who is twice as old as she．
　她不打算和一个比她大一倍的人出去散步。
　You’ve made just as many mistakes as I have．
　我和你犯的错误一样多。
　　We’ve produced twice as much cotton this year as we did lastyear.
　　我们今年的棉花产量是去年的两倍。
　　
四、as…as结构的另一变体形式是“as＋形容词原级＋名词词组＋as”
　　I don't want as expensive a car as this.＝I don't want a car as expensive as this．
　　我不要这么贵的汽车。
　Tony is as clever a boy as his brother．
　托尼是一个和他兄弟一样聪明的男孩。
　　
五、当as…as与表示重量、数量、时间、距离、价格等的计量名词连用时。往往并不表示比较。而是构成一个形容词组，意为“重达……，多达……，高达……”等。
　The river is as deep aslO meters．
　这条河深达10米。
　Frosts often occur as late as May．
　 往往到5月份还有霜。
六、“as+原级+as any(或ever)”、“as+原级+as…can be”、“nothing(或no)＋so＋原级＋as…”等结构表达的是最高级意义。即在某种程度上或某方面达到极限或最大限度。
　　He is as great a mathematician as any．
　　他是一位非常杰出的数学家。
　　He is as happy as happy can be．
　　他幸福无比。
　　No one is so deaf as those who won’t listen．
　　最聋者莫过于不听劝说的人。
　　
七、as…as…不表示比较的几个常见句型。
1．as…as possible／sb can尽可能的……
　　Please answer my question as soon as possible．
　　请尽快回答我的问题。
　　The detective is searching the man as carefully as he can．
　　那个侦探正在尽可能仔细地搜查那个男子的身体。
2．as…as usual／before像以前一样……
　　She looks as pretty as before．
　　她看起来和以前一样漂亮
　　Though they failed，they still worked as hard as usual．
　尽管他们失败了，但他们仍像以前一样努力工作。
3．as long as只要，引导条件状语从句
　I will stay with you as long as there is a room flree．
　要是你有一间空余的房子，我就住在你这里。
　You may borrow this book as long as you promise to give itback．
　　只要你答应归还，你就可以把这书借走。