It is said that in Australia there is more land than the government knows what to do with it.

问题描述:

It is said that in Australia there is more land than the government knows what to do with it.
这个句子中than 后是个什么从句吗?末尾为什么要那个it?

than 后面的是介词than的宾语从句,“what to do"是know 的宾语从句 “with it” 是个方式状语,修饰动词do,it代指land