could have done
别妄想泡我
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2020年08月02日 02:46
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考点之二：must have done表示对过去已经发生过的情况的肯定推测判断，语气较强，意思是“一定……、肯定……”。其否定形式分别用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，因为今晨地面是潮湿的。
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。
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’t
This cake is very sweet. You ___ a lot of sugar in it.
Ａ. Should put B. could have put C. might put D. must have put
--- Tom is never late for work. Why is he absent today?
--- Something ___ to him.
A. must happen
B. should have happened
C. could have happened
D. must have happened
I was on the highway when this car went past followed by a police car. They ___ at least 150 kilometers an hour.
A. should have been doing B. must have been doing
C. could have done D. would have done
I ____ have been more than six years old when the accident happened.
A. shouldn’t B. couldn’t C. mustn’t D. needn’t
1. I didn’t hear the phone. I ____ asleep.
A. must be B. must have been C. should be D. should have been
2. --- I rang your home yesterday. A man answered but I didn’t recognize the voice.
--- On, it ___ my brother, Peter.
A. must be B. must have been C. can have been D. might be
三、may/ might have done也用于对已经发生过的情况的肯定推测判断，但语气稍弱，意思是“可能，或许……”。例如：
She didn’t get there in time. She may have missed the bus.
她没能及时到达那儿。她可能没赶上汽车。
He didn’t come to school today. He might have been ill.
他今天没来上课，他可能病了。
巩固练习：
1. Sorry, I’m late. I ____ have turned off the alarm clock and gone back to sleep again.
A. might B. should C. can D. will
2. The window was broken. Tom ____ have done that, for he was a little naughty.
A. could B. might C. should D. ought to
3. Yesterday, Jane walked away from the discussion. Otherwise, she ___ something she would regret later.
A. had said B. said C. might say D. might have said
答案简析：
这三句表达的都是对过去已经发生过的情况的推测判断，意思是“可能、或许……”，应该用may/might have done结构。答案分别选ABD。
三、如果对过去情况推测判断的句子是疑问句和否定句，只能用can／could和can’t,／couldn’t。例如：
He can’t have gone abroad; I saw him an hour ago.
他不可能去国外，我一个小时前还见到他呢。
--- Can he have passed the exam? --- No, he ca
n’t have. He didn’t work hard.
他通过考试了吗？不，他不可能通过考试。他学习不努力。
巩固练习：
1.--- There were already five people in the car but they managed to take me as well.
--- It ___ a comfortable journey.
A. can’t be B. shouldn’t be C. mustn’t have been D. couldn’t have been
sister met him at the Grand Theatre yesterday, so he ____ your lecture. (2002 上海)
A. couldn’t have attended B. needn’t have attended
C. mustn’t have attended D. shouldn’t have attended
3. My English-Chinese dictionary has disappeared. Who ___ have taken it? (2003 上海春招)
A. should B. must C. could D. would
4. I didn’t see her in the meeting-room this morning. She ____ at the meeting. (1995 上海)
A. mustn’t have spoken B. shouldn’t have spoken
C. needn’t have spoken D. couldn’t have spoken
答案简析：
1、根据They were already five people in the car, but they managed to take me as well.一句中的时态，应该是对过去情况的推测判断，因为车上已经有5位人了，在带上我一个，可以断定这一定是一次不舒适的旅行。所以，本句表达的是对过去否定的推测判断，应该用can’t/ could have done来表达。故答案选D。
2、根据句意“我妹妹昨天在大剧院见过他”，所以，一定是对过去已经发生的否定的判断，答案选A。
3、本句表达的是对过去发生过的情况的疑问，所以应该用could have done，答案选C。
4、本句表达的是过去已发生情况否定的推测判断，应该用couldn’t have done，故答案选D。
四、含有must/ may/ might表示对过去情况推测判断的句子，如果变成反意疑问句，反意疑问句中动词应与情态动词must等后的动词形式保持一致，用一般过去时或现在完成时。例如：
He must have been living here for years, hasn’t he?
他一定是在这儿住了好几年了，是吗？
You can’t have slept well last night, did you?
你昨天晚上没睡好，是不是？
巩固练习：
1: Great changes must have taken place in the village in the past few years, ____ they?
A. mustn’t B. haven’t they C. can’t D. didn’t
2. He must have lived a happy a few years ago, ____ he?
A. didn’t B. hasn’t C. mustn’t D. can’t
答案简析：
1. 含有must表示推测判断的句子，其反意疑问句的动词形式应与must后动词时态保持
一致。可以理解成如果不表示推测判断，该句应该说成：Great changes have taken place in the village in the past few year. 变成反意疑问句后应该说成：Great changes have take place in the past few years, haven’t they? 所以，该题选B。
2. 本句中must后的动词形式应为did，所以，反意疑问句的动词应为didn’t。故答案选A。
五、should/ ought to have done表示“本来应该做的，而实际上没有做
的事情”，其否定形式则表示“已经做了不该做的事情”，含有责备的意思。例如：
The flowers have died. I should have watered them often.
这些花儿都死了。我本来应该常给他们浇水的。（其实没浇水）
You ought not to have told them the truth.
你本不应该告诉他们真相的。（其实你告诉他们了）
巩固练习：
1. There was a lot of fun at yesterday’s party. You ___ come, but why didn’t you? （99 上海）
A. must have B. should C. need have D. ought to have
2. Oh, I am not feeling well in the stomach, I ____ so much fried chicken just now. (2002 上海春)
A. shouldn’t eat B. mustn’t have eaten C. shouldn’t have eaten D. mustn’t eat
3. I was really anxious about you. You ___ home without a word. (NMET 2001)
A. mustn’t leave B. shouldn’t have left C. couldn’t have left D. needn’t leave
4. Mr. White _____ at 8:30 for the meeting, but he didn’t’ show up.
A. should have arrived B. should arrive
C. should have had arrived D. should be arriving（04广西卷）
六、needn’t have done表示“做了本来不必做的事情”，通常不用于肯定句。例如：
It’s only five minutes’ walk. We needn’t have taken a taxi.
只有5分钟的步行路程，我们本不必乘出租车的。
It is warm today. You needn’t have worn your coat.
今天天气暖和，你本来不必穿大衣的。
巩固练习：
1. He is not poor. You ____ have lent him the money.
A. can’t B. needn’t C. couldn’t D. mustn’t
2. There was plenty of time. You ___ have hurried.
A. won’t B. mustn’t C. needn’t D. couldn’t
答案简析：
1. 该句的意思是：他不穷，你本不必借给他钱。答案选B.
2. 该句的意思是：时间充裕着呢，你不必慌忙。答案选C。
七、can/ could have done表示“本来能够做而实际上没有做的事情”。例如：
You could have come here a little earlier.
你本来可以早点来到这儿的。
She could have earned a lot of money.
她本来可以挣一大笔钱的。
巩固练习：
He paid for a seat, when he ___ have entered free. (05 山东)
A. could B. would C. must D. need
I ____ here in time, but I met an old friend of mine. I stopped and talked with him for some time.
A. shouldn’t have come B. must have come
C. needn’t have come D. could have come
2. They ____ have finished the work yesterday, but it was raining hard.
A. must B. could C. should D. might