in

季节、年份、某月某日的早上或下午或傍晚、某一天（日期）

on

月份、某一天（

星期几

）

at

时间（几点）、晚上

in

Spring,

in

2008,

in

July

1st,

in

the

morning,

in

the

afternoon

,

in

the

evening

on

July,

on

Monday

at

18:00,

at

night