有时候，机会难得，错过了参与某事的最佳时期，也就没办法挽回了。因此，late in the day引申为了为时已晚;坐失良机。

【例句】
It's a little late in the day to start talking about policy changes.
现在开始谈论改变政策，已有点为时过晚。

He started working hard much too late in the day ─ he couldn't possibly catch up.
他开始努力工作已为时太晚——不可能赶上了。