4．Using AI，many companies are now conducting experiments that__________ possible just a few years ago．
A．would have beenB．might have been
C．shouldn't have beenD．couldn't have been
【答案】D
【解析】
考察情态动词，题干中的he wasn’t certain说明他可能不来，可能来，因此使用不完全否定，might not。
3．They were abroad during the months when we were carrying out the investigation, or they __________to our help.
比如本题，根据语境可知，这句话是父亲对子女的允诺，故选D。
2．—I don’t really like Janes. Why did you invite him?
—Don’t worry. Hecome. He said he was’t certain what his plans were.
A．must notB．need notC．would notD．might not
A．mustn’tB．shouldn’tC．wouldn’tD．mightn’t
【答案】C
【解析】
考查情态动词。句意：“数天后，我弟弟打电话说他很好，但不肯告诉我他在哪里。”mustn’t“禁止”；shouldn’t“不应该”；wouldn’t“不情愿”；mightn’t“不可能”。
11．It_____ have been Tom that parked the car here, as he is the only one with a car.
如果“must + have +过去分词”句型与by now连用，还可以表示对现在完成的动作和状态的肯定推测，但实质上还是指所推测的过去的动作。例如：
They started early this morning; they must have arrived by now.他们今晨很早就出发了，现在肯定已经到了。
【点睛】
情态动词+ have done结构：
1.“must + have +过去分词”表示对过去发生的事情或状态进行推测，语气比较坚定，通常只用于肯定句。如：It must have rained last night,for the ground is wet.
2.“can / could + have +过去分词”表示对过去某种情况的怀疑或不确定。can和could一般用于否定句和疑问句，could的语气较can弱。如：He can't have finished the work so soon.
Somebody must have stolen the ring.肯定有人偷了这枚戒指. [该句所推断的偷窃动作发生在过去.]
The temperature must have dropped to below zero last night, because the water is frozen all over.昨夜的温度肯定降到零度以下，因ave +过去分词”表示对已发生的动作或存在的状态进行不肯定的推测，might的语气比may弱一点。这种结构主要用于肯定句和否定句，疑问句改用can或could。如：They may not have known it beforehand.
4.“need + have +过去分词”表示过去做了不必做或不需要做的事情，或过去做某事纯属多余。如：I needn't have bought so much wine—only five people came.
5.“should / ought to + have +过去分词”表示过去本该做某事但没做，其否定式表示过去不该做某事但做了，这种句式含有不满或责备之意，ought to的语气比should强一些。如：
You ought to / should have studied harder.你本应该更努力学习的.（但没有）
He oughtn't to / shouldn't have done that.他本来就不该做那件事.（可是做了）
6.“would＋have＋过去分词”表示对过去的某种情况进行猜测，或本来要做某事却因某种原因未做成，通常用来说明某一情况，但不像用should或ought to那样含有责备之意。如：
I guess the poet would have been about twenty when she wrote her first poem.
Another worker wouldn't have acted like that.
6．It is really cold and the ground is wet; it ________ have rained last night.
must have done用法辨析
must have done：表示对过去的肯定的逻辑推测，推定某件事情、动作或状态可能在过去发生过（存在过）。
He must have been a doctor, for he knows medicine so well.他过去肯定是一位医生，他对医学如此了解。
情态动词易错题及解析
一、单项选择情态动词
1．—Daddy, would you please buy me an iPhoneX?
—If you can pass this midterm examination, you __________ have one as a reward.
A．mustB．need
A．mightB．must
C．canD．should
【答案】B
【解析】
【详解】
考查情态动词辨析。句意：天气很冷而且地面是湿的，昨晚一定下了雨。根据上文the ground is wet可知，“昨晚下了雨”是肯定的，故用must have done“必定做了……”表示对过去十分有把握的推测，故选B。
【点睛】
中国学生的常见病句是：They...; they certainly have arrived.病句的句义是“他们当然已经到达了。”（这不是对过去的肯定推测，而是断定动作已经完成。）
7．The room is so clean. He ________ have cleaned it yesterday evening.
9．would可以表达过去常常做的事，过去习惯发生的动作：
Pirates would bury gold in a cave.海盗们常常把黄金藏在山洞中。
We would take a walk along the river.我们过去常常沿河散步。
3. would后接like、love、mind等动词，表示要求、邀请、希望或询问，此时不是说过去，而是对现在的询问：
— Well, if you__________. I can put on more clothes.
A．canB．may
C．mustD．shall
【答案】C
【解析】
【详解】
考查情态动词。句意：-不好意思，我把窗户打开你介意吗?-好吧，如果你必须这么做的话。我可以多穿点衣服。A. can能够；B. may可能；C. must一定；必须；D. shall会；将。must表示偏要，必须要做的事情，故选C。
2. shall用于第一人称，表示征求对方的意愿。如：What shall we do this evening?
3. shall用于第一、第三人称疑问句中，表示说话人征求对方的意见或向对方请示。如：Shall we begin our lesson? When shall he be able to leave the hospital?
【答案】D
【解析】
【详解】
考查情态动词表推测。句意：很多公司现在使用人工智能进行试验，这在几年前是不可能的。根据“a few years ago”可知，此处表示“过去不可能”，应该用couldn’t have done，故D项正确。
5．The accident which left 15 people on board dead ________ if both the angry female passenger and the bus driver had kept calm.
C．wouldD．shall
【答案】D
【解析】
【详解】
考查情态动词。句意：爸爸，你可以给我买部iPhone X吗？--如果你通过考试，你就会得到一部作为奖励。A. must一定；B. need必要；C. would将，会；D. shall会。根据语境可知，这句话是父亲对子女的允诺，故选D。
【点睛】
shall的用法。
A．willB．need
C．canD．must
【答案】D
【解析】
【详解】
考查情态动词表推测。句意：房间如此干净，他一定是昨天晚上打扫过了。must have done表示对过去发生的事情有把握的猜测，意思是“一定（做过）”，故D项正确。
8．— Excuse me, do you mind if I open the window?
Would you like to come to my party?你愿意来我的派对吗？
Would you mind coming with us?你介意和我们一起吗？
比如本题，would表示婉转的请求，征求对方的意见，故选A。