通常由as或than引起，这类从句和大多数状语从句不同，它们不修饰动词，而是修饰as，so，less，more等副词，或其他比较级的词，如 taller， harder．在这里讨论它们，不是作为动词修饰语，而是作为一种状语从句。包含这类从句的句子通常为L，即从句在后：

She is as tall as I am（or me）．

He works as hard as his brother（does）．

He does not work as hard as his brother．

He does not work so hard as his brother．

No other men work as（or so） hard as his brother （does）．

No other men work as hard as does his brother．

She is taller than I（or me）．

She is taller this year than（she was tall）last year．

She is more shy than usual．

She thinks more about her appearance than（she thinks about） her personality．

She finds it easier to read than to write．

She is not taller than I．（Both are tall．）

She is no taller than I．（Both are short．）

I cannot persuade him any more than your persuade a pillar．（= I am unable to persuade him，just as you are unable to persuade a pillar．）

I can forget her no more than she（forgets）me．

Nothing is more dangerous than that you （should） make friends with him．

I will help you rather than that you（should）have any trouble．

It is better that we should die rather than that we（should）be slaves．

He is only less silly than（= almost as silly as）John．

Than him nobody is more clever．（= He is the cleverest man．）（than在这里的作用更接近介词）

Than this there are no better places．（This is the best place．）

I know John，than whom I have never seen a sillier man．

比较状语从句(adverbial clause of comparison)从某种角度上说，它也是一种方式状语从句，它通常可和以下关联词来引导as(或so)...as, than, according as, in proportion as等。如：

as...as...

He woke up as suddenly as he had fallen asleep. 他醒来得和入睡一样突然。(第一个as是副词)

I have never seen so much rain as fell that February. 我从未见过像那个二月那么多雨。(否定结构常用so…as, 也可用as... as)

than

Man developed earlier than people think. 人类的出现比人们所想的要早。

He moves more slowly than his sister does. 他行动起来比他妹妹慢。

The youth of today are better off than we used to be.今天的年轻人比我们过去的境况要好。

according as

You may go or stay, according as you decide. 是去是留由你自己决定。

You will be praised or blamed according as your work is good or bad. 你受表扬还是责备得看你的工作好坏决定。

in proportion as

Men are happy in proportion as they are virtuous. 人之幸福与德行成正比。

Some people are happy in proportion as they are noticed. 有些人越受到注意就越高兴。

The most…in/of

This book is the most interesting of the three.这本书是三本中最有趣的。

the + 形容词+est…of/in

This road is the busiest street in our city. 这条路是我们城市最繁忙的街道。

no more than只不过(嫌少的意思)

I have no more than two pens.我只有两支笔。

It’s no more than a mile to the shops.去商店不过一英里。

not more than不如。。。；(前者不如后者)

Jack is not more diligent than John.捷克不如约翰勤奋。

one of the + 名词(复数)….之一(用于最高级)

Han Mei is one of the best students in our school. 韩梅是我们学校最好的学生之一。