without facts, we cannot form a worthwhile opinion, for we need to have factual knowledge____our thinking
A.which to base upon B.which to be based upon
C.to which be based upon. D. upon which to base
请解释原因
分析一下
因为our thinking should be base upon the factual knowledge，所以factual knowledge是 be based upon的，即，我们的想法要建立在真理之上，以事实为基础，即后者是“被为基础”的，所以选B。（概念有点搅，不知道这样解释你明白不。）...
