is known to us all, only the theory on practice can be practical.
A. Which; base
B. Which; based
C. As; based
D. As; basing
网友回答
A. Which; base
B. Which; based
(答案→)C. As; based
D. As; basing
解析：考察定语从句和固定搭配。本题第一空是非限制性定语从句，which引导的非限制性定语从句不能放在句首，as指代后面一句话的内容，在句中作主语。第二空是固定搭配be based on…以…为基础。使用了based on practice来修饰名词theory。句意：众所周知，只有以事实为基础的理论才是适用的。故C正确。