close the stable door after the horse has bolted

US /kloʊz ðə ˈsteɪbl dɔːr ˈæftər ðə hɔːrs hæz ˈboʊltɪd/
UK /kloʊz ðə ˈsteɪbl dɔːr ˈæftər ðə hɔːrs hæz ˈboʊltɪd/
"close the stable door after the horse has bolted" picture
1.

亡羊補牢, 事後諸葛亮

to take precautions after a misfortune has already happened

:
Trying to fix the security breach now is like closing the stable door after the horse has bolted.
現在才試圖修復安全漏洞,就像是亡羊補牢
They should have implemented stricter rules earlier, but it's too late now; they're just closing the stable door after the horse has bolted.
他們本應早些實施更嚴格的規定,但現在為時已晚;他們只是在亡羊補牢