We were sad to know that about 30 kids had been killed in Sandy Hook, Newtown, the USA December 14, 2012.
A. in
B. at
C. on
D. by
网友回答
A. in
B. at
(答案→)C. on
D. by
解析：在表示时间时,in表示在一个时间范围;at表示在具体时刻;on表示在具体某一天.by表示到某时为止。本句中December 14, 2012为具体某一天,故用介词on,选C.