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used to say that it is possible for somebody/something to do something, or for something to happen （表示有能力做或能够发生）能，会 I can run fast. 我能跑得快。 🔊🔊 Can you call back tomorrow? 明天你能回电话吗？ 🔊🔊 He couldn't answer the question. 他不能回答那个问题。 🔊🔊 The stadium can be emptied in four minutes. 这个体育场能让观众四分钟全部离场。 🔊🔊 I can't promise anything, but I'll do what I can. 我不能许诺什么，但会尽力而为。 🔊🔊 Please let us know if you cannot attend the meeting. 你若不能参加会议，请通知我们。 🔊🔊
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used to say that somebody knows how to do something （表示知道如何做）懂得，会 She can speak Spanish. 她会讲西班牙语。 🔊🔊 Can he cook? 他会做饭吗？ 🔊🔊 I could drive a car before I left school. 我在中学毕业前就会开车了。 🔊🔊
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used with the verbs ‘feel’, ‘hear’, ‘see’, ‘smell’, ‘taste’ （与动词 feel、hear、see、smell、taste 连用） Grammar Point can / could / be able to / managecan / could / be able to / manage- Can is used to say that somebody knows how to do something:
can 表示懂得做 ：Can you play the piano? 你会弹钢琴吗？
该词亦与表示看见、注意到等的动词连用 ：I can hear someone calling. 我听见有人在呼叫。
- Can is also used with passive infinitives to talk about what it is possible to do:
The podcast can be downloaded here. 播客可在此下载。
- Can or be able to are used to say that something is possible or that somebody has the opportunity to do something:
can 或 be able to 表示某事情有可能或某人有机会做某事 ：Can you/are you able to come on Saturday? 你星期六能来吗？
- You use be able to to form the future and perfect tenses and the infinitive:
用 be able to 构成将来时、完成时和动词不定式 ：You’ll be able to get a taxi outside the station. 在车站外可搭乘出租车。 I haven’t been able to get much work done today. 我今天未能干多少工作。 She’d love to be able to play the piano. 她很希望能弹钢琴。
- Could is used to talk about what someone was generally able to do in the past:
could 表示过去通常能做 ：Our daughter could walk when she was nine months old. 我们的女儿九个月大就会走路了。
- You use was/were able to or manage (but not could) when you are saying that something was possible on a particular occasion in the past:
关于在过去特定情况下可能的事用 was/were able to 或 manage，但不用 could ：I was able to/managed to find some useful books in the library. 我总算在图书馆找到了一些有用的书。 - I could find some useful books in the library.
We weren’t able to/didn’t manage to/couldn’t get there in time. 我们未能及时赶到那儿。
亦可用 could 加表示看见、注意到、明白等的动词表示此义 ：I could see there was something wrong. 我发觉出事了。
- Could have is used when you are saying that it was possible for somebody to do something in the past but they did not try:
表示过去有可能做某事但没有做，用 could have ：I could have won the game but decided to let her win. 我本可以赢得那场比赛，但还是决定让她赢了。
- Can is used to say that somebody knows how to do something:
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used to show that somebody is allowed to do something （表示允许）可以 -
used to ask permission to do something （请求允许）可以 Which Word? can / maycan / may- Can and cannot (or can’t) are the most common words used for asking for, giving or refusing permission:
can 和 cannot（或 can't）是表示请求、给予或拒绝许可的最通用词 ：Can I borrow your calculator? 我可以借用你的计算器吗？ You can come with us if you want to. 如果你愿意可以跟我们一起来。 You can’t park your car there. 你不能在那儿停车。
- May (negative may not) is used as a polite and fairly formal way to ask for or give permission:
may（否定式 may not）用以表示礼貌的正式请求或给予许可 ：May I borrow your newspaper? 把你的报纸借我看行吗？ You may come if you wish. 你想来的话可以来。
该词常用于正式标志和规定 ：Visitors may use the swimming pool between 7 a.m. and 7 p.m. 访客从早 7:00 到晚 7:00 可在游泳池游泳。 - Students may not use the college car park.
现代英语几乎不用 mayn't。
- Can and cannot (or can’t) are the most common words used for asking for, giving or refusing permission:
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used to ask somebody to help you （请求帮助）能 -
used to make suggestions （提出建议）可以 We can eat in a restaurant, if you like. 如果你愿意，我们可以去餐馆吃饭。 🔊🔊 I can take the car if necessary. 如果必要的话，我可以乘汽车去。 🔊🔊
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used in the negative for saying that you are sure something is not true （用于否定句，表示某事肯定不真实） That can't be Mary—she's in New York. 那不可能是玛丽，她在纽约呢。 🔊🔊 He can't have slept through all that noise. 他不可能在那种闹哄哄的环境里睡好觉。 🔊🔊
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used to express doubt or surprise （表示疑惑或惊讶）究竟能，难道会，到底是 used to say what somebody/something is often like （表示常有的行为和情形）有时会，时而可能 - (informal)
used to say that somebody must do something, usually when you are angry （表示对方必须做，通常指说话人在生气时）必须，得 Grammar Point modal verbsmodal verbs- The modal verbs are can, could, may, might, must, ought to, shall, should, will and would. Dare, need, have to and used to also share some of the features of modal verbs.
- Modal verbs have only one form. They have no -ing or -ed forms and do not add -s to the 3rd person singular form:
- He can speak three languages.
She will try and visit tomorrow. 她明天将设法去参观。
- Modal verbs are followed by the infinitive of another verb without to. The exceptions are ought to, have to and used to:
情态动词后跟不带 to 的动词不定式，但 ought to、have to 和 used to 例外 ：You must find a job. 你必须找到一份工作。 You ought to stop smoking. 你应当戒烟。 I used to smoke but I gave up two years ago. 我过去抽烟，但两年前就戒了。
- Questions are formed without do/does in the present, or did in the past:
疑问句现在时不用 do/does，过去时不用 did ：Can I invite Mary? 我可以邀请玛丽吗？ Should I have invited Mary? 我本该邀请玛丽吗？
- Negative sentences are formed with not or the short form -n’t and do not use do/does or did.
Word OriginOld English cunnan ‘know’ (in Middle English ‘know how to’), related to Dutch kunnen and German können; from an Indo-European root shared by Latin gnoscere ‘know’ and Greek gignōskein ‘know’.
Idioms
as happy, simple, sweet, etc. as can be
as happy, etc. as possible 尽可能地快乐（或简单、甜等）
can’t be doing with somebody/something | can't be doing with somebody doing something
no can do
