○一天中特定的时间，也就是几点几分用at:
I have to turn in this report at 3:00.我必须在3点交出这份报告。
AT 5:00 I leave the office no matter what is happening.不管发生什么事，我会在5点下班。
○一条中的某个时段要用in：
in the morning/afternoon/evening,at night
I like to drink coffee and read the newspaper in the afternoon.我喜欢在下午喝咖啡看报纸。
He always gets lost at night.
○月份要用in：
This year I suggest we take vacation in August.我建议我们今年8月去度假。
My uncle wants to visit us in January.我叔叔1月想来看我们。
○年份要用in：
He graduated from college in 1995.他1995年从大学毕业。
The company was founded in 1888.这家公司创立于1888年。
○季节要用in：
Mosquitoes bite most in summer and fall.
○星期要用on：
We are going to meet at the night market on Friday.我们星期五约在夜市见面。
On Saturdays I always sleep late.星期六我总是睡到很晚。
○星期几的某个时段也要用on：
I like to watch movies on Friday nights after the kids go to bed.我喜欢在星期五晚上孩子们都上床后看电影。
○周末常用on：
On weekends I catch up with all my housework.我都在周末把所有的家务做完。
○假日期间用at，假期当天用on：
We see her every year at Thanksgiving.我们每年感恩节都会去看她。
We stay up to see in the New year on New Year’s Eve.我们会在除夕夜彻夜不眠迎接新年。
○日期要用on：
Valentine’s Day is on February 14th.情人节时2月14日。
My wife’s birthday is on July 10th.我太太的生日是7月10日。
○比较在月份和日期这样的时间的表达：
Let’s go in September.我们9月去吧。
I am free on September 26th.我9月26日那天有空。
Are you free at the night on that day?你那天晚上有空吗？
○若已经使用了this,next,every,tomorrow或yesterday等表示某特定时间，便不可以再加in，on 或 at：
Are you free this afternoon?