第26题: [单项选择]All the lights ______ before we left the office. A. has been turned off B. have turned off C. had been turned off D. had turned off 参考答案:C 答案解析:[考点] 时态和语态 [解析] 此句中主句的动作在从句的动作之前,而从句的动作发生在过去,所以主句应该用过去完成时,因为all the lights和turn off之间是被动关系,所以应该用被