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。