It was April 29 2001Prince William and Kate Middleton walked into the palace hall of the

问题补充：

It was April 29, 2001Prince William and Kate Middleton walked into the palace hall of the wedding ceremony.

A. that

B. when

C. since

D. before

答案：

A. that

(答案→)B. when

C. since

D. before

解析：句意：当威廉王子和凯特米德尔顿步入了皇宫大厅举行了结婚仪式是四月29日。这题容易错选成that，以为是强调句，但是判断是否是强调句的方法是去掉强调结构，这句话仍然成立就是强调句，这句话去掉强调句是：Prince William and Kate Middleton walked into the Palace hall of the wedding ceremony April 29,,缺少介词on，所以不是强调句，那么理解成when引导的时间状语从句，前面的it是表示时间，所以答案要选B。