Question

All the guests at the party were dancing and singing happily _____ the electricity was cut off.

A．until

B．while

C．when

D．because

Answer 1

C

试题分析：句意：当电源被切断后，聚会上的所有客人都高兴地又唱又跳。Until直到；while然而；when当……时候；because因为，选C。