具体某一天前用on,如on Children's Day
星期前用on,如on Saturday
具体某一天的早上,下午,晚上用on 如on the morning of July 2nd ,on a cold winter afternoon
月份前用in 如in June
今天晚上一般说成 this evening ,前不用介词,如I will go to the movies this evening.
另外,再告诉你年份和季节前用in