Traveling by train is a lot more fun than taking a bus中为什么要用a lot more

问题描述:

Traveling by train is a lot more fun than taking a bus中为什么要用a lot more
是因为后面的fun是形容词吗,若不是请说明原因

fun在此是名词,因为more有形容词的词形啊,修饰fun