That must be a lot more fun than taking a bus. 这里面为什么用taking?

问题描述:

That must be a lot more fun than taking a bus. 这里面为什么用taking?
因为than是介词还是因为动名词做主语?()

than 是介词,介词后用动词的ing形式.
除非是习惯用语,比如had better do sth than do sth.
其他时候都必须用ing