so..as和as..as的区别?

在意思上它们是不一样的,在否定句中既可以用not as ...as...也可以用not so...as,而在肯定句中只能用as...as.．．
He is as clever as you.(He is not as/so clever as you.)
但下面的句子要特别注意：
1) I'll come back as soon as possible.
2) The clouds are as white as snow.
3) He is so strong as to lift a big stone.(so...as to do:那么．．．．．．以至．．．．．．）

as...as用在肯定句里，so ... as用在否定句或疑问句里。
Tom 和Jim一样高
Tom is as tall as Jim
Tom 和Jim不一样高
Tom is not as tall as Jim
Tom is not so tall as Jim（有Tom 不及Jim高的意思）