老版新概念三第一课[A Puma at Large]课后练习题求解2

题目

老版新概念三第一课[A Puma at Large]课后练习题求解2
12 A private collector is a man who collects .(lines 15-16)
a. for his own benefit b. on his own c. in private d. unknown to the public
我的选择是（c）,正确答案是（a）,why?

答案

不要从语法的角度去想这个问题,用常识来解释啊!
偷偷的收藏?说得过去吗?肯定是为了收益而收藏啊!
说明你专注于做题,而不思考!