表示时间in( ) on( ) at( )

in Tanuary, in winter, in 1999;泛指在上午,下午,晚上,如：in the morning(afternoon, evening). 习惯用法：in the daytime 在白天. ②on指在某一天或某一天的上午,下午,晚上,如：on Monday, on Sunday afternoon, on July 1, 1999 ③at时间最短,一般表示点时间,如at six o’clock, at three thirty.习惯用法：at night, at noon, at this time of year.