单选题Theprofessorcouldhardlyfindsufficie

单选题 The professor could hardly find sufficient grounds ________ his arguments in favor of the new theory．A.on which to baseB.which to base onC.to base onD.to be based on

A解析题意为“教授几乎找不到支持这一新理论的充分理由”。根据题意，题中的professor是想将自己的argument建立在sufficient grounds之上，即to base his arguments on these sufficient grounds。因此，关系代词which指代先行词grounds，作介词on的宾语。

就是这个解释