at/on/in?(time)

指明時間，好似下午一時正，就用at，即at 1:00pm
指明日期，尤其係星期幾或那一天，
例子：Monday, Tuesday,Wednesday...都係用on
that day, second day...
仲有，好似20thJanuary,2006咁都係用on
指明年份同月份，就用in，
例子：January, February, March... 1997、1998、2006等都係用in

所有指定時間都用at
指定日期就用on
年月就用in喇
有咩唔明再問我la

in除了以上，還可以用在seasons,parts of day(in summer,in evening[s])
at除了以上，還可以用在meals,festival(at breakfast,at Christmas)
資料不足！！

我既英文老師教左我一個易記d既方法..
就係...
in 　> 　1日　　即係多個1日,in summer,in May,in 2005
on 　= 　1日　　即係1日,on the 19th Oct, on Monday
at 　<　1日 　　即係少過1日, at the moment,at night, at present

當然,有exception~
in the morning/afternoon..etc
at christmas,at easter... etc

個人認為好有用,因為佢講之前我都唔識分,宜家已經記得到(好易記)
in>on>at

at seven o'clock.
on Monday, on 24th March, 2006.
in 1991 or in the morning