ave been prosperous， for it enjoyed a high level of civilization.
4） needn’t have + 过去分词
表示过去不必做某事，但已经做了，即本可不必做某事。
You needn’t have woken me up. I don’t have to go to work today.
He needn’t have watered the flowers， for it is going to rain.
5） should / ought to have + 过去分词
表示过去应该做某事而实际上没有做。
You should / ought to have done what your parents told you. （But you failed to do it.）
You should / ought to have been more careful. （But you weren’t.）
6） shouldn’t / oughtn’t to have + 过去分词
表示过去不应该做某事而实际上却做了。
You shouldn’t / oughtn’t to have crossed the road when the lights were red. （But you did.）
They shouldn’t / oughtn’t to have left so soon. （But they did.）
7） would have + 过去分词
表示对现在或将来某时之前业已完成的动作的推测。可译为，“可能”、“也许”、“想必”。
He would have arrived by now.
She would have recovered by then.
[ 结 束 ]