is well known is the Diaoyu Islands have been part of China since ancient times.
A. Which; that
B. That; which
C. What; that
D. That; what
网友回答
A. Which; that
B. That; which
(答案→)C. What; that
D. That; what
解析：考察名词性从句。第一空What引导主语从句what is well known且在句中作主语。第二空that引导表语从句that the Diaoyu Islands have been part of China since ancient times.此句子结构很完整，只需要使用that引导，that在句中不充当任何成分，只起引导作用。句意：众所周知的事情是钓鱼岛自古以来就是中国的一部分。故C正确。