介词at用来表示特定的时间、节日、年龄等。如:at noon
介词for 表示一段时间如:I have been living here for 10 years.
更多资料请见http://www.360doc.com/content/11/0830/14/7447651_144479967.shtml
at 用于一天当中的时间:Millie has breakfast at seven o'clock
年龄:Children in China start school at 6 years old
on用于星期几:we do not go to school on Saturday
日期:our summer hoilday starts on July1
特殊的一天某个时间:amy goes swimming on Sunday morning
特殊节日:they have lots of fun on Children's Day
有描述性短语修饰:on a cold winter morning
in用于一天某一时间:my parents watch TV in the morning
月份、季节、年份:in March、in winter、in 2013
for用于一段时间:i will go on a trip to Shanghai for two days
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