1. 形容词的用法：形容词可在句中作

1) 定语
Look at the beautiful moon!

2) 表语
This book is both interesting and instructive.

3) 宾语补足语
He is always keeping his room clean and tidy.

4) 相当于名词（形容词前加the）
He has a keen sense of the new.

2. 形容词的表现形式

1) 比较级：用于两者的比较。其表现形式为 - 含有形容词比较级的主句+从属连词than引导的从句（从句中常省去意义上和主句相同的部分）。如：
She is older than my mother. （从句中省略了is old）
There are more students in this class than in that one. (从句中省略了there are students)
After two years in the countryside my father is healthier. (从句中省略了than he was)

2) 最高级：用于两者以上的比较。其表现形式为 - 定冠词the + 形容词最高级 +名词+表示范围的短语或从句.
Xiao Liu is the most diligent student in our class.
This is the best film I have ever seen.
Do you know the tallest man?

3) 同级：
a. as…as: 表示……相等(一样)……；
This knife is as sharp as that one. （从句中省略了is）
This box is as heavy as that one. （从句中省略了is）

b. not as … as 或 not so … as: 表示……不相同(不一样) ……
He is not as tall as his father.（从句中省略了is）
She is not so beautiful as I have expected.

4) 几倍于：用twice（两倍）, three times（三倍）等加as…as。如：
Shanghai is ten times as big as my hometown (is).
The output of this shirt factory is now twice as high as it was last year.

5) 表示程度：用much, far, still, even, a little, no, any, a great of等状语来修饰形容词或副词的比较级。如：
The Yellow River is long, but the Yangtze River is even longer.
You should study even harder to achieve still greater victory.

6) "比较级+and+比较级" （后面不可接than从句）表示 "越来越……"。如：
The days are getting longer and longer.
I rely more and more on his help.

7) the + 形容词或副词比较级… the+形容词或副词比较级的用法: 意思是"越……，就越……"。如：
The harder you study, the better grade you will get.
The sooner, the better.
越快越好。

8) more than和 less than 这两个固定词组分别表示"多于"，"少于"。如：
Our university has established relationships with more than sixty countries.
We finished our homework in less than three hours.
不到三小时我便完成了家庭作业。

9) all the better 和so much the better 均有"因此更…"的含义.
If that is so, all the better.
如果情况是这样的，那更好。
If he will come, so much the better.