The professor could hardly find suffient grounds _______ his arguments in favor of the new theory.
A.to be based on B.to base on C.which to base on D.on which to base
为什么C选项不行?我咋觉得C D可以替换
回答时尽量详细
要解释另三个选项为啥不行
就这么多了.
thank you~