形容词和副词的比较级和最高级的构成分为三种类型：

1）在大多数单音节词和少数双音节词的词尾加er，est。
（1）一般情况在词尾加-er，est。如：hard harder hardest
（2）以字母e结尾的只加-r，-st。如：large larger largest
（3）以辅音字母+y结尾的，先改y为i，再加-er，est。如：healthy healthier healthiest
（4）单元音单辅音结尾的重读闭音节，先双写该辅音，再加-er，est。如：thin thinner thinnest
注：词尾为ow，er，le结尾的双音节词都采用这种形式。如：
narrow         narrower             narrowest
clever          cleverer              cleverest
simple         simpler               simplest

2）在多音节和部分双音节词的词前加more，most。另外，由过去分词转化而成的形容词，不论多少个音节都用这种形式。如：
serious        more serious        most serious
popular       more popular        most popular
tired           more tired            most tired
pleased       more pleased       most pleased

3）不规则变化：
good/well            better                    best
bad/ill/badly        worse                    worst
many/much          more                     most
little                   less                      least
far                      farther/further        farthest/furthest
old                      older/elder            oldest/eldest

形容词和副词的比较级和最高级的用法

1）同级比较。常用句型为：
肯定结构：as+形容词（副词）原级+ as
否定结构：not so (as)+形容词（副词）原级+as如： Our garden is as beautiful as theirs.
Jane didn't write as/so carefully as her elder sister.
上述本句型前可以有表示倍数或分数的修饰语，如：This room is three times as large as that one.

2）程度不等的比较，常与than连用，其基本句型是： A+形容词（副词）比较级+ than B
如：
Shanghai is bigger than any other city in China. Which do you like better, strawberries or grapes?

3）最高级。最高级用于三者或三者以上的比较，其结构是：
the+形容词（副词）最高级+比较范围（of/among/in短语） 如： Spring is the best season in Shanghai.
David is the cleverest among the three brothers. Tom jumps (the) farthest of all the students.
注：副词的最高级前the可以省略。

学习比较等级时的—些注意事项

1）比较的对象应当一致。如：
It's hotter in Guangzhou than Beijing.（误）
It's hotter in Guangzhou than in Beijing.（正）
A woman's heart beats faster than a man.（误）
A woman's heart beats faster than a man’s.（正）

2)不能与自身相比较。应借助other或else来表达排除。
如：
Beckham is more popular than any football player in the world.（误） Beckham is more popular than any other football player in the world（正）
Beckham is more popular than all the other football players in the world.（正）
Beckham is more popular than any football player, else in the world.（正）
Beckham is the most popular football player in the world.（正）

3)形容词和副词的比较级前可以用以下单词来修饰：much, even, far, a bit, a little, a lot，still等。
This pair of shoes is even cheaper.
The new textbook is a little thicker than the old one.
He is five years younger than I.

4)在比较级的句子中出现“of the two”之类的结构时，比较级前也需加定冠词the。如：
He is the shorter of the two boys.
Which is the larger country, Canada or Australia?

5)“比较级+ and+比较级”结构，表示“越来越……”，多音节词则要用“more+ and+more+原级”。如：
A block of ice is becoming smaller and smaller.
I am more and more interested in history.

6)“the+比较级，the+比较级”结构，表示“越是……就越”。如：
The sooner, the better.（越快越好。）
The busier he is, the happier he feels.