单选题
2分
The factory operated__________ until the order was filled.
参考答案: D
参考解析: 句意:工厂昼夜不停地工作,直到交付订单为止。at times“有时”;to the minute“恰好,一分不差”;day by day“一天天”;around the c|ock“昼夜不停”。