I can't pay as ( )as he asked for A .high price B .high a pr

B.主要考察as +adj+n+as与n+as+adj+as的用法
只要记住一点就明白了：as 必须且只能用来修饰形容词,如果as被用来修饰一个名词,肯定就错了.
例如I can't buy as good a book as that one.这句正确,因为as是和good一起用的,非用来修饰名词book,因为有一个a阻止了as和book之间的联系（这句话如果没有a就是错误的）.
as good books as这短语中心词是books,很显然as是用来修饰books的,所以就错误.
你的问题同我讲的例句一样.