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
网友回答
A. which to be based on
B. which to base on
(答案→)C. on which to base
D. which to base
解析：base A on B把A建立在B的基础上。