这个结构用来表示没有覆行义务或不明智地忽略了该做的事。在否定式中这一结构表示从前发生的、错误的或愚蠢的事。

You ought to have told him that the paint on that seat was wet．

你本应该告诉他椅子上的油漆还没有干。

You should have turned his omelette；he likes it turned．

你本应该给他摊的鸡蛋翻个身的；他喜欢吃两面都煎透的摊鸡蛋。

They ought to have stopped at the traffic lights．

他们本应在红绿灯处停下。

She shouldn't have opened the letter；it wasn't addressed to her．

她不应该拆开信，信封上写的不是她的名字。

The Emergency Exit doors shouldn't have been blocked．

紧急出口的门本来不应被堵死。