object lesson

1. N-COUNT If you describe an action, event, or situation as an object lesson, you think that it demonstrates the correct way to do something, or that it demonstrates the truth of a particular principle. (作教训或原理的)实例[oft N 'on/in' n]

It was an object lesson in how to use television as a means of persuasion. 这是利用电视作为劝导方式的一个实例。