Without facts we can’t form a correct opinion for we need to have actual knowledge our

问题补充：

Without facts, we can’t form a correct opinion, for we need to have actual knowledge our thinking.

A. which to be based on

B. which to base on

C. on which to base

D. which to base

答案：

A. which to be based on

B. which to base on

(答案→)C. on which to base

D. which to base

解析：“没有事实根据，我们不能形成一个正确的观点，因为我们需要以事实为基础进行思考。”knowledge是先行词，后面的定语从句缺少宾语，指物用which或that，介词后只能用which。故选C。