情态动词+have done 用法 1. Something may have happened to her. 她可能发生了什么事情。 She might have had an accident. 她或许遭受了意外. So she must have taken that too. 因此，她肯定把它也带走了。 1) 这三句话都用了“情态动词＋不定式的完成时”，表示对发生过的事作某种猜测、推测。 (1) must have done 可用来对某件过去的事情作肯定推测，表示“一定已经，想必已经”做过某事，用于肯定的陈述句中。否定句中用 can't have done。 She must have received the parcel, I sent it by registered post. 她一定已经收到包裹了，我是用挂号寄的。 (2) may have done, might have done, could have done “可能做过某事”，就语气而言 could have done 所表的可能性更小些。 He may / might / could have left by nine. 他可能于九点前已离去。 (3) should have done / ought to have done 表示“本该做某事”但实际未做。 I should / ought to have left London before nine but I didn't. 我本该在九点以前离开伦敦，但是我没有。 (4) shouldn't have done / oughtn't to have done 表示“本不该做事”，但实际上又做了。 He shouldn't / oughtn't to have left London before nine but he did. 他本不该在九点前离开伦敦，但是他离开了。 (5) can't / couldn't have done 表否定推测，“不可能做过某事”。 She can't / couldn't have gone to bed, for the light in her room is still on. 她不可能上床睡觉了，因为她房间的灯还亮着。 (6) could have done 可表示客观上“本来能做某事但实际上没做”。 He could have finished the work in time but he didn't work hard. 他本来可以按时干完活的，但他没有卖力。 (7) needn't have done 表示客观上“本不必做某事但实际上又做了”。 I needn't have gone to the office yesterday (but I went there). 昨天我没必要去办公室（但我却去了）。 (8) might have done 还可表示过去“本可能发生但实际上没有发生的动作”。用于表示说话人对已发生的事提出批评或意见。 He might have given more help, even though he was very busy. 即使他很忙，也可以多帮点忙。 ...
