Tom runs twice as fast as Mike.汤姆跑得速度是迈克的二倍。
(2)“甲+助动词+not+动词原形+as/so+副词原级+as+乙”甲不如乙…例如：
He doesn’t walk as slowly as you.他走路不像你那样慢。

二、比较级的用法
1.可以修饰比较级的词，much，a lot，far，…的多； a little，a bit，…一点儿； even甚至;；still仍然。例如：
Lesson One is much easier than Lesson Two.第一课比第二课容易得多。
Tom looks even younger than before.汤姆甚至比以前更年轻。
This train runs much faster than that one.这辆火车比那辆跑地快。
She drives still more carefully than her husband.她开车仍然比她丈夫还认真。

2.比较级常用的句型结构
(1)“甲+实意动词+(倍数)+副词比较级+than+乙”表示“甲比乙…”或“甲比乙…几倍”。例如：
I got up earlier than my mother this morning.我今天早晨起床比我妈妈还早。
He runs three times faster than his brother.他跑的速度比他弟弟快三倍。
(2)“甲+实意动词+副词比较级+than+anyother+单数名词(+介词短语)”表示“甲比同一范围的任何一个人/物都……”，含义是“甲最……”。例如：
Mike gets to school earlier than any other student in his class.
= Mike gets to school earlier than any of the other students in his class.迈克比他们班上任何一个其他的同学到校都早。
= Mike gets to school earlier than the other students in his class.迈克比他们班上其他的同学到校都早。
= Mike gets to school earliest in his class.迈克在他们班到校最早。
注意：Mike gets to school earlier than any student in Tom’s class.迈克比汤姆班上任何一个学生到校都早。(迈克和汤姆不是同一个班)
(4)“比较级+and+比较级”表示“越来越……”。例如：
He is getting taller and taller.他变得越来越高了。
The flowers are more and more beautiful.花儿越来越漂亮。
He does his homework more and more carefully.他做作业越来越认真了。
(5)“the+比较级，the+比较级”表示“越……，越……”。例如：
The more careful you are，the fewer mistakes you’ll make.你越认真，犯的错误越少。
(6)“特殊疑问词+实意动词+副词比较级，甲or乙？”例如：
Who draws better，Jenny or Danny？谁画得比较好，詹妮还是丹尼？

三、最高级的用法
最高级常用句型结构
(1)“主语+实意动词+(the)+副词最高级+单数名词+in/of短语”表示“……是……中最……的”。例如：
I jump (the) farthest in my class.我是我们班跳得最远的。
(2) “特殊疑问词+be+the+副词最高级+甲，乙，or丙？”用于三者以上的比较。例如：
Which season do you like (the) best，spring，summer or autumn？你最喜欢哪一个季节，春天，夏天还是秋天？
(3)“特殊疑问词+be+the+最高级+甲，乙，or丙？”用于三者以上的比较。例如：
Which country is the largest，China，Brazil or Canada？哪一个国家最大，中国，巴西还是加拿大？