Question

The professor could hardly find sufficient grounds ________ his arguments in favor of the new theory．

1. A.
   on which to base
2. B.
   which to base on
3. C.
   to base on
4. D.
   to be based on

Answer 1

A
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。