英语比较级：同级比较（The Positive Degree）
同级比较，就是比较后的结果是“和……一样”或“和……不一样”。同级比较的重点是两者一样不一样，并不是要分出谁好谁坏。所以，它的形容词和副词不需要进行变化，即所谓的“原级”。它的表达方式是：
(1) 两个一样： as + 形容词或副词的原级 + as
这个结构的核心是 as...as。在英语里，as 有“如同……”、“像……”的意思。请注意：这里用的是两个 as。这种表达方式翻译成中文就是：A和B一样。例如：
This building is as beautiful as that of yours.
这座大楼和你们的大楼一样漂亮。
It is clear that she can run as fast as you.
很显然，她跑得和你一样快。
His bedroom is as neat as his sister's.
他的寝室没有他姐姐的整洁。
(2) 两个不一样：否定句+ so (as) + 形容词或副词的原级 + as
表示“不相同”，一般都简写为 not so/as...as 。但我发现，部分学生会误认为not 与 so/as 是紧密连在一起的。 其实不是，not 在这里代表“否定句”，所以not 与 so/as 有时会隔得很远。另外，表达“不一样”时，not... so...as 与 not...as...as 都可以用，但习惯上用not...so....as 多一些。这种结构的中文意思是A和B不一样。例如：
He is not so tall as his brother.
他没有他的父亲高。(结构：is not / as tall as )
These books are not so cheap as those.
这些书没有那些书偏宜。(结构：are not / so cheap as )
It is not so hot as yesterday.
今天不象昨天那么热。
Actually you didn’t write as carefully as your desk mate.
事实上，你写得没有你的同桌写得仔细。(结构：didn't write / as carefully as )
I can't speak English as fast as a native speaker.
我说英文没有以英语为母语的人说得快。(结构：can't speak / as fast as )
She hasn't been quite so unlucky as she pretends.
她还没有像她常装出的那样不幸。(结构： hasn't been / so unlucky as )
(3) 同级比较结构的变化
同级比较结构 as .... as 与 not...so/as...as 是个基本的结构。在具体运用时，还有一些细节上的变化。
第一、(倍数、程度等) as ...as
在as … as 的结构中，第一个as的前面可以加上表示倍数的词、或是某些副词修饰语：twice , three times , nearly , almost , just , exactly , not nearly（根本不）, by no means, quite 等等。例如：
Asia is four times as large as Europe.
亚洲有欧洲的四倍大。
Cast iron is almost as useful as steel.
铸铁差不多与钢一样有作用。
James is not nearly as tall as Robert.
詹姆斯根本没有罗伯特高。(is not / nearly / as tall as )
She hasn't been quite so unlucky as she pretends.
她还没有象她常装出的那样不幸。( hasn't been / quite / so unlucky as)
第二、as much + (不可数名词等) + as ， as many + (复数可数名词等) + as
一般情况下，as ... as 中间都是形容词或副词，但有时候as ... as 中间也可加入名词，变成了as ..形容词 + 名词等 as 的结构。例如：
This is as good an example as the other is.
这个例子跟那个例子一样好。( as good ... as )
She spreads as much butter on her bread as Jane usually does.
她在面包上涂的黄油与琼通常涂的一样多。(as much ... as )
He has learned as many English words as his brother (has ) .
他已学了和他哥哥一样多的英文单字。(as many ... as)
There are more than twice as many books as five years ago.
现在有超过五年前两倍以上的书籍。(more than twice / as many ... as )
I can carry as much paper as you can.
你能搬多少纸，我也能搬多少。
参考资料：http://www.mrshen.com/EngClass/ShowArticle.asp?ArticleID=583