马后炮

(a Chinese chess term used figuratively to mean) belated action or advice; belated effort

♦ 切记不要使问题成了堆, 才来一个总结, 放~。 Make sure that you don't wait until problems pile up before making a reckoning —that would be firing belated shots.

♦ 我这个建议也许是~。 It's probably already too late for my suggestion to do any good.