有一读者来信说：我们的语法书上讲“should have+过去分词”都是用以表示过去应发生而未发生的事，如：
(1)You should have seen the film.
但我遇到下面一段对话：
(2)— Now, Nils, let us have a talk.
— Can we have anything to talk about?
— We have a great deal to talk about.
— I shouldn't have thought so.
请问这里的 shouldn't have thought 是什么意思？
“should have+过去分词”除可表示过去应发生而却未发生的事之外，还可用以表示其他一些情况。你所举“I shouldn't have thought so.” 中的 shouldn't have thought 只是其中的一种情况。这种“should have+thought”已成为一种比较固定的说法，常用以表示非常谦逊委婉、语气不肯定（其程度还要胜过 should think）, 再如：
(3)I should have thought you might control yourself.
(4)I should have thought it rather unfair.
上述 should have thought 皆意谓“认为”，但有时则可意谓“本以为”或“本认为”（而这正是 should have thought 的本义）， 如：
(5)— Can you eat any meats?
— Certainly.
— Funny. I should have thought you wouldn't.（这里的 should 常可被 would 所代替）
下面一句中的“should have+thought”是用在虚拟语气中：
(6)I should have thought my work half completed had I made it a mere register of verbal distinctions.
再如：
(7)If ever she should have hated Basil, it was now.
下面句子中的 should 则表“可能”：
(8)I think it should have worked by this time.
下面一句中的 should 则与 why 连用：
(9)Why should that have been enough?
