问题补充：
Without facts , a person can’t form a correct opinion , for he needs to have actual knowledgehis thinking .
A. which to be based on
B. on which to base
C. which to be based
D. which to base
答案：
A. which to be based on
(答案→)B. on which to base
C. which to be based
D. which to base
解析：本题可采取增元法。把句子的后半部分补全为：for he needs to have actual knowledge on which he bases his thinking . base on：建立……基础上。如Parents owe their children a set of solid values around which to build their lives。故选B。
