题目内容：

9.He will leave for Beijing __________April 4th and come back __________ June.
9.He will leave for Beijing __________April 4th and come back __________ June.A.in; on B.on; on C.in; in D.on; in

优质解答

选D,on  
1）表示具体日期.  
they arrived in shanghai on may  
25．他们在五月二十五日到达上海.  
in  
1）表示"时段"、"时期",在多数情况下可以和dur- ing互换,前者强调对比,后者强调持续.in（during）1988（December,the 20th century）在一九八八年（十二月、二十世纪）  
i returned to Beijing in the middle of June．我是六月中回北京的.但如果表示"在某项活动的期间",则只能用during.  
during my military service（the trip）在我服役期间（在旅行期间）  
2）表示以说话时间为基点的"（若干时间）以后",常用作将来时态谓语的时间状语.如这时要表示"（若干时间）内",常用within.比较：  
the meeting will end in 30minutes．（三十分钟后）会议三十分钟后结束.  
can you finish it within 30minutes?（三十分钟内）你能在三十分钟之内完成这件事吗?  
 但在过去时态中,in可用于表"在若干时间以内",这时不要误用during.the job was done during a week．（wrong）  
the job was done in a week．（right）这工作在一星期内就完成了.