1.月份,年份前用介词in: In January,2005 / 2005年元月 2.几点钟前用介词at at two /在两点 at 7p.m/在下午七点 3.it lasts ( for) three hours. for表持续时间 这次会议已经持续了两小时了. The meeting has lasted for two hours. 4.表具体某一天或星期几,用介词on. 从那时起,新年就在一月一日. From then on,New Year's Day was on January 1 on Monday,在周一.