1. fewer and less区别
2.amount 不可数

补充 as many 的用法

1. as many的用法(摘自Longman):
as many=a number that is equal to another number 表示同样的数字
They say the people of Los Angeles speak 12 languages and teach just as many in the schools.
in as many days/weeks/games etc.
A great trip! We visited five countries in as many days (=in five days).
*: "twice as many", "one-quarter as many", etc.都是非常常见的用法，记住这样的表达。