军考英语：易混英语词汇辨析：a second

　　54. a second, the second

　　a second 又一，再一;

　　the second 第……，例：He won the second prize.

　　55. by day, by the day

　　by day 白天;

　　by the day 按天计算，例：The workers are paid by the day.