比较状语从句是主从复合句，所以它由两部分构成：主句和状语从句。主句和从句存在着比较关系。一般模式为：主句+连词+比较状语从句。常用连词或结构有：as；as …as, not as/ so … as；than；:the more … the more … ; just as …, so…; A is to B what /as X is to Y; no … more than; not A so much as B
1.比较
同级比较： as...as 引导的比较状语从句；as 引导的比较状语从句；not so/as...as "引导的比较状语从句；as many/much a引导的比较状语从句。
例如：She is as bad-tempered as her mother.
There are almost as many definitions of history as there are historians.有多少历史学家，就有多少历史学的定义。
That's not so/as simple as it sounds.那件事情不像听起来那么简单。
不同级比较： than引导的比较状语从句；more...than引导的比较状语从句；less...than引导的状语从句。
例如：You look younger than you are. 你看上去比你的实际年龄要年轻。
2.倍数：表达倍数也是一种比较。常用：是......倍，可以用N times as much as来表达;多......倍，可以用”more than/less than”来表达；是百分之几，则可以用N%来表达。
The house is three times as big as ours.
There are only half as many fisheries as there were 15 years ago. 如今的渔场数量仅是15年前的一半。
其他：the..., the...引导的比较状语从句；not …so much as引导比较状语从句；“not….any more than”比较状语从句；“no more ….than”引导的比较状语从句；no less than. 引导的状语从句；not any less than”引导的状语从句。
如：Mary is no more diligent than Tom.就意为Mary和Tom都不勤奋。
The more you study, the more knowledge you can get. 你学的知识越多，你的知识越丰富。
The great use of a school education is not so much to teach you things as to teach you the art of learning.学校教育的重大作用，与其说是交给你东西，不如说是交给你学习的艺术。
省略和替代：
比较状语从句中，若存在相同性质的比较对象，会出现表达的重复，所以会使用替代和省略。
例如：James enjoys the theater more than Susan does .(动词替代）
Contrast may make something appear more beautiful than it is when seen alone.（it is后省略了 beautiful）。
