3） be supposed to have done = should have done = ought to have done 表示“过去本该做某事但实际上未做”。
I’m supposed to have handed in a first draft of my dissertation.
The train is supposed to have arrived an hour ago. 火车应该在 1 小时前到达。
What am I supposed to have done wrong now?
The first debate was supposed to have been held on Tuesday.
‘The President cannot be disturbed,’ his son is supposed to have told an early morning caller.
3. suppose 可用过去完成时表示“未曾实现的愿望”\“原以为”。
We had supposed that we would be able to see more of Shanghai, but time didn’t permit. 我们本打算能多看看上海，但时间却不允许了。
I had supposed his wife a younger woman.
She had supposed him very rich.
注意：与 suppose 这种用法相同的还有： hope, think, expect, mean, want, intend, plan (一些表示心理状态的动词)等。
4. suppose 可用于“ suppose + that (从句)”句型。
I suppose we’ll go there next week.
What makes you suppose (that) I’m against it? 你根据什么认为我反对这件事?
It was generally supposed that it would not happen again. 一般认为此事不会再发生。
5. 由 suppose 引导的宾语从句，如果主句的主语是第一人称 I 或 we ，并且主句谓语是一般现在时态，从句的否定一般要转移到主句上来，其反意疑问句一般与宾语从句一致。
I don’t suppose for a minute that he’ll agree. 我认为他决不同意。
We don’t suppose they will say sorry to her, will they? 我们认为他们不会对她说对不起，是吧?
在英语中，含suppose的句子是用否定主句谓语的方式来否定后面宾语从句的内容的(即把宾语从句的否定词 not转移到否定主句谓语动词上来)，这种语言现象叫做转移否定，在这种用法中，suppose意为“想，认为，猜想，料想”;宾语从句是由that引导的宾语从句，也是由否定词 not构成的否定，主句主语多为第一人称。如:
I don’t suppose I’ll trouble you.