to be wise after the event 

used to mean that it is easy to understand what you could have done to prevent something bad from happening after it has happened

事后聰明很容易;放馬后炮很容易

In retrospect, we should have insisted on checking his calculations, but it's easy to be wise after the event.

回想起來(lái)，我們本該堅(jiān)持檢查他的計(jì)算結(jié)果，不過(guò)事后聰明倒是容易。

（素材來(lái)自每日學(xué)英語(yǔ)，如有侵權(quán)請(qǐng)聯(lián)系刪除）