Casual workers are usually paid ______ the hour.
A. by B. on C. to D. with
答案是 by。但为什么不能是 on 呢？on the hour 的搭配我也见过。如：
A bus leaves for New York on the hour.
...ear-old girl was thrust into the shelter. He hastily fought the door latch on again, then stared at the frightened little newcomer in anger, hating her for simply being there in his wife's place and knowing he could not turn her out. fight是打架、战斗的意思。fight on 译文...