"in/on the morning of October 20"?

http://www.merriam-webster.com/dictionary/morning
例句: She arrived on the morning of March 18.


我之前在AUE上問的一個問題。

"in the morning of October 20"?

(很多時候我都忘了我曾在那裡問過什麼問題,所以我會開始把一些我自己想要記得的問題放在這裡,免得忘光光)


"on the morning" vs. "in the morning"?
http://www.englishforums.com/English/MorningMorning/cqmlj/post.htm