题目

form a worthwhile opinion for we need to have factual knowledge ___ our ...
This sentence is from an exercise book.The whole sentence is:
Without facts,we cannot form a worthwhile opinion for we need to have factual knowledge ___ our thinking.
The correct answer of the blank is:on which to base
The red colour part make me confused.
I hope somebody could be telling me the structure of the sentence.I can't fully understand such sentences.
请帮我理解从空处开始向後的这个部分

提问时间：2021-01-06

答案

参考答案:请记得,好朋友的定义是：你混的好,她打心眼里为你开心；你混的不好,她由衷的为你着急.