It is too late for a galloping horse to stop at a clip; it is useless for a sinking boat to be mended in the middle of a river.

It is too late for a galloping horse to stop at a clip; it is useless for a sinking boat to be mended in the middle of a river.

亡羊补牢，为时已晚。沉船在河中央修理是没有用的。