时间点前用at

We have class at eight o'clock.

星期几，具体日期，具体到某一天的上午/下午/晚上，节日前用on

We play football on Sunday.

John's birthday is on November 20th.

What do you have on Sunday afternoon?

They will have a party on Children's Day.

年份，月份，笼统的上午/下午/晚上前用in

Mike will be 18 years old in 2030.

Is it hot in July（七月）here?

I get up at 6:30 in the morning.