The park is quite different from what it was three years ago.这里为什么用what?
问题描述：
The park is quite different from what it was three years ago.这里为什么用what?
答
表示这个公园与3年前大不一样
from 后是what 引导的宾语从句
what it was three years ago= the park that (可见：what=先行词+ 关系代词）it was three years ago