是on the day星期，日，月，都要用on 比如：on that day, on Friday，on March年用in 比如：in 1999.但是如果年月日一起就用on,比如：on the 1st, 1999.(只要有日，就用on)
具体某天用介词onOn that raining day,I met my friend.
on the day
