“马后炮”本是一个象棋术语，意思是在“马”后面加一颗“炮”，将对方的军（check, put the other player’s king under direct attack）。
后来人们用“马后炮”比喻事后采取措施，无济于事；或事情发生后才提出批评或建议，表示自己有先见之明的人（a person who criticizes or suggests alternative courses of action from a position of hindsight after the event in question），也称“事后诸葛亮（second guesser, be wise after the event）”。
- 考试都完了，你才说帮我复习功课，这岂不是马后炮吗？
You come and offer to help with my lessons only after the examination. Isn’t that a bit too late? - 他是个马后炮。
He is a second-guesser. - 事后诸葛亮人人都会做。
It is easy to be wise after the event.
