Correct
贼走关门
/ zéi zǒu guānmén /
Strokes
Example
Definition
lock the door after the thief has gone; lock the stable door after the horse is stolen—take action only after the harm is done; it is already too late to mend
lock the door after the thief has gone; lock the stable door after the horse is stolen—take action only after the harm is done; it is already too late to mend