It was April 29, 2011 Prime 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：考查固定句型。句义：威廉王子和凯特-米德尔顿走进婚姻殿堂的时间是2011年4月29日。根据句首It was+时间排除C D ,固定句型：It is/was …that …强调句型，it was +时间点+ when…当…的时候，时间是… ，排除A，所以B正确。