情态动词表示推测
情态动词表推测的三种时态
1.对将来情况的推测，用“情态动词 + 动词原形”
（1）She must / may / might / could arrive before 5.
5:00前她一定/可能/也许到。
（2）She must/may/might/could walk miles and miles among the hills without meeting anyone. 她一定/可能/也许会在山里一连走好几英里而遇不到一个人。
2.对现在或一般情况的推测，用“情态动词 + be”，“情态动词 +be doing”或“情态动词 + 动词原形”。
（1）He must / may / might / could be listening to the radio now.
他一定/可能/也许正在听收音机。
（2）He can’t ( couldn’t ) / may ( might ) not be at home at this time
这个时候他不可能可能不在家。
（3）Mr. Bush is on time for everything .How can ( could ) he be late for the opening ceremony ? 布什先生一向准时，这次开幕式他怎么可能迟到呢？
3.对过去情况的推测，用“情态动词 + have +过去分词”。
（1）It must / may / might / could have rained last night .The ground is wet
地湿了，昨晚肯定/可能/也许下雨了。
（2）The door was locked. He can ( could ) not / may ( might ) not have been at home .
门锁着，他不可能/可能不在家。
说明：
(1) may / might + have done
含义1：表示对过去事实不大肯定的推测。常译为，可能已经
附：通常用于肯定句和否定句。 might有时可用于疑问句。
eg.①They might have taken a later train. 也许他们乘坐的是晚一点儿的火车。
②He seems to know the city quite well. He may have been there before
他似乎对那个城市很熟悉，他以前可能去过那儿。
含义2：表示本来应该或可以做但没有做某事（含有轻微的责备口吻或遗憾）
eg :①The proposal might have been refused. 这个建议本该拒绝的
(2) can / could + have done
含义1：表示对过去事实的推测。常译为：可能做了
附：通常用于疑问句和否定句。could有时可用于肯定句。
eg.①He can't /couldn't have watched TV yesterday for he knew they would have an exam.
昨天他不可能看电视，因为他知道快要考试了。
②He didn't come to school yesterday. Can he have been ill?
他昨天没来学校，难道他生病了吗?
含义2. could + have done 可表示对过去能做而未做
（可译成：本来是可以……的 ）
eg.①Why didn't Sophia apply for the job? She could have got it.
为什么索菲不申请这项工作？她本来是能得到的。
②Given more time, we could have done the work better.
如果给我们更多的时间，我们完全可以把这项工作干得更好。
(3) must + have done
含义1：具有较大的可能性。常译为：一定已经
eg.①His watch must have stopped. 他的表肯定停了。
含义2：用于虚拟语气中时，表示与过去事实相反。
eg.①He 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（事实上他没赢）
注意：在反意疑问句中，疑问部分的助动词应与must后面的动词在非推测情况下的时态保持一致。
He must be a worker, isn`t he? （现在）他准时个工人，是吗？
It must have rained last night, didn`t it? （过去）昨晚一定下雨了，是不是？
You must have learned English for many years, haven`t you? （完成时）你一定学了好多年英语，是吗？
(4) should + have done和ought to + have done
含义1：表示本来应该做某事而实际上未做，对过去动作的责备或批评。
（shouldn’t have done则表示“本不应该做某事而实际上做了）
eg.①You should have gone over your lessons.
你们应把功课复习好的。(可事实上你们没有。)
②You 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。
含义2.表示期待或推测。（将来的事情）
eg.①If 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。
②The 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。
（5）would + have done
含义：表示与过去事实相反的假设或结果。
eg.①I 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。
②If 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。
(6) needn't have done
含义：用于对过去的责备，表示没有必要做某事，可是做了
附：只用于否定句
eg.①The 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)
②He 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： 表示过去不必做也没有做之意，需用didn't need to do
eg. 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)。
PS:
必背：英语口语中dare的几个常用结构：
● I dare say... 我想, 大概, 可能, 或许…
eg. I dare say things will improve. 我想情况会好转的。
● How dare you ... 你怎么敢……？
eg. How dare you ask me such a question? 你怎么敢问我这样的问题？
● I dare you ... 我谅你也不敢……
eg. I dare you to tell your parents! 我谅你也不敢告诉你父母！
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