I'll meet you __three o'clock __the afternoon__October 12th.

问题描述:

I'll meet you __three o'clock __the afternoon__October 12th.

I'll meet you at three o'clock on the afternoon of October 12th.
表示某个时间点的时候,要用at
通常说“在下午”是用in the afternoon,但说某具体日期的下午就要用on the afternoon
用of 是因为在某一天的下午,这里可以把October 12th 看成是afternoon的定语