导读：情态动词表示说话人对动作或状态的各种观点和态度，如需要、猜测、意愿或怀疑等。情态动词有词义，但不完全，是所谓的“辅助性”动词，在句中不能单独充当谓语。下面长沙新东方高考频道带着大家开始今天的情态动词的相关语法学习，小伙伴们每天学一点，一起拿下高考英语语法，加油吧!

　　C：must have done

　　1.表示对过去事实有把握的推测，具有较大的可能性。只用于肯定句中，否定句和疑问句用can/could have done。

　　His watch must have stopped.他的表肯定停了。

　　--- I rang your flat yesterday. A man answered but I didn't recognize the voice.昨天我给你家打电话，一位男士接了电话，但我没听出来是谁的声音。

　　--- Oh, it must have been my brother Peter. 哦，那一定是我哥哥彼得。

　　2.用于虚拟语气中时，表示与过去事实相反。

　　You must have caught the bus if you had got up earlier. 如果你早一点儿起床的话，你准能赶上那一班公共汽车了。(事实上没有赶上公共汽车)

　　He must have won the game if he had been careful enough.如果他足够细心的话，他准能赢得比赛。.

　　D：needn't have done

　　用于对过去的责备，表示"没有必要做某事，可是做了"。

　　The airport is close to us. You needn't have hurried there early.机场离这儿很近，你没必要早早地赶到那里。(可是你早早地到那儿了)

　　He is still young. You needn't have sent him such an expensive present.他还小，你没必要送他这么昂贵的礼物。

　　注意：

　　如表示"过去不必做也没有做"之意，需用didn't need to do。

　　It is not cold today. I didn't need to take the thick sweaters out.今天天气不冷，我没有必要把厚毛衣拿出来。(实际上也没拿)

　　E：should/ought to have done

　　1.表示对过去动作的责备或批评。

　　You should have gone over your lessons. (In fact you didn't go over your lessons.)你们应把功课复习好的。(可事实上你们没有。)

　　You shouldn't have watched TV last night. (In fact you watched TV last night.)你们昨天晚上本不该看电视。(可你们看了。)

　　You oughtn't to have entered the teachers' office without permission.没有经过允许，你们本不该进老师的办公室。

　　You oughtn't to have gone to the deserted place alone. 你不该独自去那荒凉之地。

　　F：would have done

　　表示与过去事实相反的假设或结果。

　　I would have been happy to see him, but I didn't have time.我会很高兴和他见面的，但我没时间见他。

　　If your father had still been alive, he would have felt very proud of you.你父亲如果还健在的话，他会为你骄傲的。

　　2.表示期待或推测。

　　If the flight was on time, you should ought to have arrived in Shanghai early this morning.如果航班准点的话，你今早就能到上海了。

　　The building should ought to have been completed by the end of the week.这幢建筑物本周末前应该能完工。

　　(来源：新东方高考在线辅导)

　　延伸阅读：

　　2019高考英语专项大作战

　　2019年高考英语语法专项：情态动词+have done(一)

　　2019年高考英语语法专项：情态动词need

　　2019年高考英语语法专项：情态动词dare

　　2019年高考英语语法专项：情态动词used to