问题
选择题
Without facts, a person can not form a correct opinion, for he needs to have actual knowledge ______his thinking .
A．on which to be based
B．on which to base
C．which to be based
D．which to base
答案
答案：B
题目分析：考查定语从句。base...on...把......建立在......的基础之上，排除C、D；base的逻辑主语是a person，与base是主谓关系，不用被动语态，排除A。故选B。