Finally I bought the new book I spent twenty yuan in the bookstore where a friend of min

问题补充：

Finally, I bought the new book,I spent twenty yuan, in the bookstore where a friend of mine is the boss.

A. on which

B. which

C. for which

D. that

答案：

(答案→)A. on which

B. which

C. for which

D. that

解析：表示在什么上花费多少钱可用spend+钱+on sth，修饰名词书是一个定语从句，书为事物，故可用which，故本题应选A。