问题补充：
The dinner didn't start ______ all the friends arrived.A.whenB.whileC.untilD.whether
答案：
C解析此题考查连接时间状语的连词，when表示①“当……时候”，如：You'd better call“110”when you are in trouble.②表示“就在那时”，如：I was just falling asleep when someone knocked at the door. while强调动作同时发生，它引导的从句中动词多为延续性动词，如：While we were talking, the teacher came in. until表示“直到……为止”，如：I'll wait until you come hack. not...until...表示“直到……才”。whether表示“是否”，相当于if。
