I'll never forget the day I bought my own guitar with my own money.
A. where
B. on which
C. on when
D. that
网友回答
A. where
(答案→)B. on which
C. on when
D. that
解析：通过分析句子结构，可知这个句子中包含一个定语从句，“介词+关系代词” 有时候相当于对应的关系副词，这里on which=when,其中介词的确定是依据先行词的某种习惯搭配确定，故选B。