It was April 29, 2011 Prince William and Kate Middleton walked into the palace hall of the wedding ceremony.
A. that
B. when
C. since
D. before
网友回答
A. that
(答案→)B. when
C. since
D. before
解析：本题考查定语从句。句意为： 2011 年4月 29 日，威廉王子和凯特?米德尔顿步入了结婚仪式的殿堂。句中缺定语从句的关系词，因先行词是 April 29, 2011 且在从句中作时间状语，故用 when 。此题易误选A，将其看作是强调句，若是强调句应在时间前面加上介词 on 。