单选题 They worked ______ day and ______ night and were paid by ______ hour.
【正确答案】 D
【答案解析】[考点] 冠词的用法 [解析] 本题中出现了两个习语,一为day and night“日日夜夜,不分昼夜”,二为pay by the hour“按小时计算”。对付这类题仍应平时多加积累,别无捷径。