问题补充：
The bride and bridegroom were wedding gifts when all lights went out and the hall fell into completely darkness and the wedding ceremony had to .
A. presenting; be put off
B. exchanging; put off
C. offering; be stopped
D. exchanging; stop
答案：
A. presenting; be put off
B. exchanging; put off
C. offering; be stopped
(答案→)D. exchanging; stop
解析：句意：在新郎和新娘正在交换结婚礼物时，这时所有的灯都灭了，大厅完全陷入黑暗中，婚礼不得不停止。这里be doing ……when……正在做某事突然发生了另一件事。exchang wedding gifts交换结婚礼物；stop不能用被动，故选D。
