can't have done和couldn‘t have done 的区别

Question

如题所述

Answer 1

从释义，用法，使用环境，形象和影响范围五个维度分析can't have done和couldn‘t have done的区别，详细内容如下。

1. 释义区别：

- "can't have done"的字面意思是“不可能已经做过某事”，它表示主观上持有不可能或不太可能某种行为或事件已经发生的观点。

- "couldn't have done"的字面意思是“不可能已经做过某事”，它强调过去发生的某事已经不可能发生。

例句：

- I can't have left my keys at home. I remember putting them in my bag.（我不可能把钥匙忘在家里，我记得把它们放在包里了。）

- She couldn't have stolen the money. She has been with me all day.（她不可能偷了钱，她整天都和我在一起。）

2. 用法区别：

- "can't have done"表示较为客观的不可能性，认为根据某些事实或逻辑推理，某种行为或事件不会发生。

- "couldn't have done"更强调对过去事件的否定，表达一种坚定的观点，认为某事在过去根本就不可能发生。

例句：

- He can't have finished his homework yet. He only started an hour ago.（他不可能已经做完作业了，他只开始一个小时。）

- They couldn't have won the game without your help.（没有你的帮助，他们不可能赢得比赛。）

3. 使用环境区别：

- "can't have done"常用于对过去事件或行为的推测，表示根据已有的信息或观察，认为某事在过去不可能发生。

- "couldn't have done"也常用于对过去事件进行否定推测，但语气更加坚定，强调某事在过去根本就不可能发生。

例句：

- It can't have rained last night. The ground is completely dry.（昨晚不可能下雨，地面完全干燥。）

- She couldn't have taken the car. The keys are still on the table.（她不可能拿走车子，钥匙还在桌子上。）

4. 形象区别：

- "can't have done"在形象上更接近一种猜测或推断，表示对某事的猜测或假设。

- "couldn't have done"在形象上更强调对某事不可能性的肯定表达。

例句：

- They can't have eaten all the cake. There's still a big slice left.（他们不可能吃完所有的蛋糕，还剩下一大块。）

- He couldn't have forgotten his own birthday. That's impossible.（他不可能忘记自己的生日，那是不可能的。）

5. 影响范围区别：

- "can't have done"的影响范围相对较宽，可以用于对任何行为或事件的推测。

- "couldn't have done"的影响范围相对较窄，主要用于对过去事件的否定推测。

例句：

- They can't have arrived yet. They were supposed to be here an hour ago.（他们不可能已经到达，他们本应在一个小时前到达这里。）

- He couldn't have known about the surprise party. We kept it a secret.（他不可能知道惊喜派对的事情，我们保密了。）

Answer 2

can't have done（不可能做过）是must have done（一定做过）的否定形式。

couldn't have done(可能没做过)是may have done(有可能做过)的否定形式。

一般认为can't have done有80%以上的把握.而couldn't have done则委婉的多,只有50%左右的把握.

must do /can't do一定,肯定80%把握。

may/could do/couldn't do有可能50%把握。

might do/mightn't do也许大概差不多30%以下的把握。

can的用法

1、can用作情态动词的基本意思是“能，能够”“可以”“可能，会”，可表示体力、智力能够完成一件事情或环境赋予的能力; 也可表示由于环境或其他因素而产生的可能性，用于疑问句或否定句中; 还可表示环境、条件或法律的许可。can也可表示要求、拜托、请求、惊讶等。

2、can可与实义动词搭配，构成动词性合成谓语，表示“能力”; 也可用在否定句或疑问句中，与be、进行式的动词或完成式的动词搭配，是对现在或过去的推测，表示“绝不可能”“难道…吗?”。

3、can与表示知觉的动词搭配使用时，通常不用于进行体。

4、can的否定式can't或cannot表示智力或体力不够、不可能或禁止。“can't help v -ing”表示“不禁…”“禁不住做某事”。

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Answer 3

首先我们来看下can't have done和couldn't have done的大致意思：

can't have done：词性为短语，can't（can not）：不能；have：已经（助动词）；done（do的过去分词）：做过

couldn't have done：词性为短语，couldn't（could not）：不能；have：已经（助动词）；done（do的过去分词）：做过

通过下面的表格我们了解下can't have done和couldn't have done的含义、发音和用法

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接下来让我们看下can't have done和couldn't have done的用法区别：

1.情态动词的不同：can't是can not的缩写形式，表示不可能；couldn't是could not的缩写形式，也表示不可能

例子：

- I can't have gone to the party last night.

(我昨天晚上不可能去参加派对。)

- He couldn't have got the secret.

(他一定没有得到这个秘密。)

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2.时间的不同：can't have done表示对过去发生的事情感到肯定不可能；couldn't have done也表示对过去发生的事情感到肯定不可能，但更强调过去动作的否定

例子：

- He can't have called me last night because I was sleeping.

(他不可能在昨天晚上打电话给我，因为我那时在睡觉。)

- She couldn't have left during the meeting.

(她不可能在会议期间离开了。)

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3.语气的不同：can't have done语气较强烈，表示非常肯定不可能；couldn't have done语气稍弱，表示相对不太可能

例子：

- He can't have seen the movie because he was working.

(他不可能看到这个电影，因为他正在工作。)

- He couldn't have attended the party because he had mentioned something else earlier.

(他不太可能去参加聚会，因为他之前说过他有其他安排。)

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4.对否定程度的不同：can't have done表示对某个动作或事件的否定程度较高；couldn't have done表示对某个动作或事件的否定程度稍低

例子：

- I can't have finished the task so quickly.

(我不可能马上完成这个任务。)

- He couldn't have found the answer in five minutes.

(他不可能在五分钟内找到答案。)

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5.语法结构的不同：can't have done使用了can的否定形式，表示对过去的否定；couldn't have done使用了could的否定形式，也表示对过去的否定

例子：

- I can't have met him last night because I was on a business trip.

(我不可能在昨天晚上见到他，因为我在外地出差。)

- He couldn't have attended the meeting because he didn't receive an invitation.

(他不可能参加了会议，因为他没有收到邀请。)

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6.可能性的不同：can't have done表示对过去发生的事情感到较大的不可能性；couldn't have done表示对过去发生的事情感到较小的不可能性

例子：

- I can't have seen him last week because I was abroad.

(我不可能在上个星期见过他，因为我当时在国外。)

- He couldn't have completed the task in such a short time.

(他不太可能在短时间内完成这项任务。)

Answer 4

can't have done（不可能做过）是must have done（一定做过）的否定形式.
couldn't have done(可能没做过)是may have done(有可能做过)的否定形式.
一般认为can't have done有80%以上的把握.而couldn't have done则委婉的多,只有50%左右的把握.
must do /can't do一定,肯定80%把握
may/could do/couldn't do有可能50%把握
might do/mightn't do也许大概差不多30%以下的把握本回答被提问者和网友采纳

Answer 5

couldn't have done和can't have done都表示不可能,是对过去情况的推测。
例句:He can't / couldn't have worked out the problem.他不可能解决了这个难题。
can't 也可以用于对现在情况推测，couldn't have done可以用 和过去事实相反的虚拟语气。
例如：If you hadn't gone to the party,you couldn't have met your future wife.如果你没去晚会,你不可能遇到你未来的妻子.