情态动词 + have done 重点1. Something may have happened to her. 她也许发生了什么事情 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＋不定式的完毕时”，表达对发生过的事作某种猜想、推测 (1) must have done 可用来对某件过去的事情作肯定推测，表达“一定已经，想必已经”做过某事，用于肯定的陈述句中否认句中用 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 “也许做过某事”，就语调而言 could have done 所表的也许性更小些 He may / might / could have left by nine. 她也许于九点前已拜别。
(3) should have done / ought to have done 表达“本该做某事”但实际未做 I should / ought to have left London before nine but I didn't. 我本该在九点此前离开伦敦，但是我没有 (4) shouldn't have done / oughtn't to have done 表达“本不该做事”，但事实上又做了 He shouldn't / oughtn't to have left London before nine but he did. 她本不该在九点前离开伦敦，但是她离开了 (5) can't / couldn't have done 表否认推测，“不也许做过某事” She can't / couldn't have gone to bed, for the light in her room is still on. 她不也许上床睡觉了，由于她房间的灯还亮着 (6) could have done 可表达客观上“本来能做某事但事实上没做” He could have finished the work in time but he didn't work hard. 她本来可以准时干完活的，但她没有卖力。
(7) needn't have done 表达客观上“本不必做某事但事实上又做了” 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 还可表达过去“本也许发生但事实上没有发生的动作”用于表达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. 虽然她很忙，也可以多帮点忙 情态动词 + 动词完毕式即“ 情态动词 + 动词完毕式即“情态动词 + have + done”，表达对过去行为或动作进行推测、评论或判断这个构造是近几年高考情态动词的重点和难点 一、在虚拟语调中的用法 1. should have done 表达“过去本应当做某事却未做其否认构造 shouldn't have done 表达 “过去本不该做某事却做了 2. ought to have done 表达“过去本应当做某事却未做其否认构造 oughtn't to have done 表达“过去本不该做某事却做了。
3. need have done 表达“过去本有必要做某事却未做其否认构造 needn't have done 表达“过去本没必要做某事却做了 4. could (不能用 can) have done 表达“过去本可以做某事却未做注意：其否认形式 couldn't have done 没有虚拟语调的用法，couldn't have done 只能表推测，相称于 can't have done，意为：“过去不也许做了某事 5. might (不能用 may) have done 表达“过去本可以做某事却未做 注意：其否认形式 might not have done 没有虚拟语调的用法，might not have done 只能表推测，相称于 may not have done，意为：“过去也许没有做某事 二、表推测的用法 1. must have done 表达对过去某事的肯定猜想，译为：过去肯定做了某事不存在 mustn't have done 的形式其否认或疑问形式须用can(could) 来表达. 例如： Since the road is wet, it must have rained last night. 既然路是湿的，那昨天晚上肯定下雨了。
He can't have missed the way. I drew him a map. 她不也许迷路我（当时）给她画了张图 “The dictionary has disappeared. Who could have taken it?”词典不见了，（过去）谁也许把它拿走了？ 2. may / might have done may / might have done 表达“过去也许做了某事”may 比 might表达的也许性在说话人看来稍大些may/might not have done表达“过去也许没有做某事例如： I can't find my keys. I may / might have left them at the school yesterday. 我找不到我的钥匙了我也许昨天把她们落在学校了John may/might not have passed the exam; he looks very sad.约翰也许没有通过考试她看起来很忧伤注意：may/might have done表推测不能用于疑问句中 3. can/could have done 表推测一般用在否认句和疑问句中，表达不相信或怀疑的态度。
Can/Could he have passed the exam?她也许通过了考试吗？ I think that he couldn’t/can't have gone abroad. I saw him just now.我觉得她不也许出国了我刚刚还看见她了 注：表达推测过去某动作发生的也许性时，就表达的也许性限度而言，must 最大，could 另一方面，may 更次之，might 最小例如：“I wonder how Tom knew about your past.” “我想懂得汤姆是怎么懂得你的过去的He must / could / may / might have heard of it from Mary.” “她肯定/很也许/也许/兴许（没准儿）已从玛丽那儿据说此事了情态动词＋have done”考点解析 “情态动词＋have done”构造是重要考点，也是较难掌握的语法项目之一，为了协助同窗们更好地掌握使用这一考点，下面结合近年高考试题谈谈其重要用法考点之一：在虚拟条件句中，如果表达与过去事实相反的状况，从句中用过去完毕时，而主句中则用“情态动词＋目前完毕时”，即：would/ could/ should/ might have done。
例如：If they had finished the work on time, they would have been praised by the manager.If you had worked hard, you could have passed the examination.考题分析：1. If it ___ for the snow, we ___ the mountain yesterday. A. were not; could have climbed B. were not; could C. had not been; could have climbed D. had not been; could climb2. --- I stayed at a hotel while in New York. --- Oh, did you? You ___ with Barbara. A. could have stay B. could stay C. would stay D. must have stay3. Yesterday Jane walked away for discussion, otherwise, she ___ something she would regret later. A. had said B. said C. might say D. might have said答案简析： 1. 根据信息词yesterday可以判断该句是表达与过去事实相反的虚拟条件句，从句中应当用“情态动词＋目前完毕时”，故答案选C。
2. 本句是一种含蓄虚拟条件句，意思是：If you hadn’t stay at a hotel while in New York, you could have stayed with Barbara. 体现了与过去事实相反的状况，答案选A3. 本句考察的也是含蓄虚拟语调，意思是：如果她参与了讨论，她也许会说出某些后来令她懊悔的话体现了与过去事实相反的状况，故答案选D考点之二：must have done表达对过去已经发生过的状况的肯定推测判断，语调较强，意思是“一定……、肯定……”其否认形式分别用can’t/ couldn’t和can/ could例如：It must have rained last night, for the ground is wet this morning.昨天晚上一定是下雨了，由于今晨地面是潮湿的She didn’t attend the lesson yesterday. She must have been ill.她昨天没有上课，她一定是生病了1. Must have done 语调极强，表达非常肯定，一定做了某事，基本只用肯定句巩固练习.He ____ have completed his work, otherwise, he wouldn’t be enjoying himself by the seaside. A. should B. must C. wouldn’t D. can’tThis cake is very sweet. You ___ a lot of sugar in it. Ａ. Should put B. could have put C. might put D. must have putI was o。