Usage note: can could be able to manageCan is used to say that somebody knows how to do something: Can you play the piano? It is also used with verbs of seeing, noticing, etc: I can hear someone calling, and with passive infinitives: The DVD can be found online.Can or be able to are used to say that something is possible or that somebody has the opportunity to do something: Can you/Are you able to come on Saturday?You use be able to to form the future and perfect tenses and the infinitive: You’ll be able to get a taxi outside the station. I haven’t been able to get much work done today. She’d love to be able to play the piano.Could is used to talk about what someone was generally able to do in the past: Our daughter could walk when she was nine months old.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: I was able to/managed to find some useful books in the library. I could find some useful books in the library.Manage is more formal and less frequent than be able to. In negative sentences, could not can also be used: We weren’t able to/didn’t manage to/couldn’t get there in time.Could is also used with this meaning with verbs of seeing, noticing, understanding, etc.: I could see there was something wrong.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: I could have won the game but decided to let him win instead.Usage note: can mayCan and cannot (or can’t) are the most common words used for asking for, giving, or refusing permission: Can I borrow your calculator? You can come with us if you want to. You can’t park your car there.May (negative may not) is used as a polite and fairly formal way to ask for or give permission: May I borrow your newspaper? You may come if you wish. It is often used in official signs and rules: Visitors may use the swimming pool between 7 a.m. and 7 p.m. Students may not use the college car park. The form mayn’t is hardly ever used in modern English.
1 used to say that it is possible for someone or something to do something, or for something to happenI can run fast.Can you call back tomorrow?He couldn't answer the question.The stadium can be emptied in four minutes.I can't promise anything, but I'll do what I can.Please let us know if you cannot attend the meeting.2 used to say that someone knows how to do somethingShe can speak Spanish.Can he cook?She could read before she started kindergarten.3 used with the verbs “feel”, “hear”, “see”, “smell”, “taste”She could feel the cool air on her face.I can hear music.4 used to show that someone is allowed to do somethingYou can take the car if you want.We can't wear jeans at work.5 (informal) used to ask permission to do somethingCan I read your newspaper?Can I take you home?6 (informal) used to ask someone to help youCan you help me with this box?Can you feed the cat, please?7 used in the negative for saying that you are sure something is not trueThat can't be Mary—she's in New York.He can't have slept through all that noise.8 used to express doubt or surpriseWhat can they be doing?Can he be serious?Where could she have put it?9 used to say what someone or something is often likeHe can be very tactless sometimes.It can be really cold here in the winter.10 used to make suggestionsWe can eat in a restaurant if you like.I can take the car if necessary.11 (informal) used to say that someone must do something, usually when you are angryYou can be quiet or get out! note at modalIDIOMS
/kən; strong form kæn/negative cannot
/ˈkænɑt; kəˈnɑt; kæˈnɑt/short form can't
/kænt/past tense could
/kəd; strong form kʊd/negative could not short form couldn't
as happy, simple, sweet, etc. as can be
as happy, etc. as possibleShopping online is as simple as can be.as happy, simple, sweet, etc. as can be