【题目】The professor can hardly find sufficient grounds his argument in favor of the theory.
A. which to base on
B. on which he bases
C. to base on which
D. which to be based
在线课程【答案】B
【解析】考查定语从句和base的用法。句意为:教授几乎找不到足够的依据来支持他的理论观点。base...on...“把……建立在……基础上”。