have done相关语法

have done相关语法

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. 情态动词 + 动词完成式即“ 情态动词 + 动词完成式即“情态动词 + have + done”,表示对过去行为或动作进行推测、评论或判断.这个结构是近几年高考情态动词的重点和难点. 一、在虚拟语气中的用法 1. should have done 表示“过去本应该做某事却未做.”其否定结构 shouldn't have done 表示 “过去本不该做某事却做了.” 2. ought to have done 表示“过去本应该做某事却未做.”其否定结构 oughtn't to have done 表示“过去本不该做某事却做了.” 3. need have done 表示“过去本有必要做某事却未做.”其否定结构 needn't have done 表示“过去本没必要做某事却做了.” 4. could (不能用 can) have done 表示“过去本能够做某事却未做.”注意：其否定形式 couldn't have done 没有虚拟语气的用法,couldn't have done 只能表推测,相当于 can't have done,意为：“过去不可能做了某事.” 5. might (不能用 may) have done 表示“过去本可以做某事却未做.” 注意：其否定形式 might not have done 没有虚拟语气的用法,might not have done 只能表推测,相当于 may not have done,意为：“过去可能没有做某事.” 二、表推测的用法 1. must have done 表示对过去某事的肯定猜测,译为：过去肯定做了某事.不存在 mustn't have done 的形式.其否定或疑问形式须用can(could) 来表示. 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. 他不可能迷路.我（当时）给他画了张图. “The dictionary has disappeared. Who could have taken it?”词典不见了,（过去）谁可能把它拿走了? 2. may / might have done may / might have done 表示“过去可能做了某事”.may 比 might表示的可能性在说话人看来稍大些.may/might not have done表示“过去可能没有做某事.”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.我可能昨天把他们落在学校了.John may/might not have passed the exam; he looks very sad.约翰可能没有通过考试.他看起来很忧伤.注意：may/might have done表推测不能用于疑问句中. 3. can/could have done 表推测一般用在否定句和疑问句中,表示不相信或怀疑的态度. Can/Could he have passed the exam?他可能通过了考试吗? I think that he couldn’t/can't have gone abroad. I saw him just now.我认为他不可能出国了.我刚才还看见他了. 注：表示推测过去某动作发生的可能性时,就表示的可能性程度而言,must 最大,could 其次,may 更次之,might 最小.例如：“I wonder how Tom knew about your past.” “我想知道汤姆是怎么知道你的过去的.”“He must / could / may / might have heard of it from Mary.” “他肯定/很可能/可能/兴许（没准儿）已从玛丽那儿听说此事了.” 参考文献： 英语空间