Question

【题目】All the guest at the party were dancing and singing happily __________ the electricity was cut off.

A. until

B. while

C. when

D. because

Answer 1

【答案】C

【解析】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。