they were an elderly couple who lived in an old house on __ was left of the family farm.
问题描述：
they were an elderly couple who lived in an old house on __ was left of the family farm.
为什么是what 不是which
不是做定语吗
答
不是,是宾从=on the things that was left of the family farm为什么不是定于？定从前面要有先行词，也就是说明的对象