亡羊补牢

HSK 7-9

wángyáng-bǔláo

to remedy after the fact; better late than never

fig. to act belatedly; better late than never; to lock the stable door after the horse has bolted

失踪后找回了狗

shīzōng hòu huíqiǎo le gǒu

Finding a dog that went missing.

知道错误后再改正

zhīdào cuòwù zài hòu lái gǎizhèng

Correcting mistakes after knowing them.