My aunt often drops by my house Sunday afternoons because I am free then.A. atB. inC. onD

问题补充：

My aunt often drops by my house Sunday afternoons because I am free then.

A. at

B. in

C. on

D. of

答案：

A. at

B. in

(答案→)C. on

D. of

解析：at表示时间的一点，in表示一个时间范围，on表示在具体某一天，of表示所有关系，根据星期日下午，选C。