object lesson
noun [ C ] approving uk/ˈɒb.dʒɪkt ˌles.ən/ us/ˈɑːb.dʒɪkt ˌles.ən/
借鉴;经验教训
an action or story that teaches you how or how not to act, or that clearly shows the facts of a situation, usually a bad one
The disaster was an object lesson in how not to run a ship. 这场灾难对于如何驾驶船只提供了经验教训。