can和could的意义.doc

can和could的意义，有能力做，有可能，可以She can lift me up with one hand . 她可以一只手把我举起来。（有能力做）Can yon swim ? 你会游泳吗？（有能力做）You can borrow my car if you want to.如果你想借我的汽车，你可以借去用。（有可能）Anybody can learn to cook. 人人都能学会做饭。（可以）It could rain later. 晚些时候可能会下雨的。（有可能）Could 不仅是can 的过去时形式，could 还可以用来表达现在和将来。You could be right. 你可能是对的。Could I see you tomorrow evening ? 明天晚上我可以见见你吗？关于can 、be able to 和could 表示“能力”的用法需要注意下面几点：1、现在和将来can 通常用来表达现在或“一般的能力”即你无论什么时候想做就能做到的能力。Look! I can do it ! I can do it !嗨，我会做这事啦！我会做啦！You can certainly cook , even if you cant do anything else. 你当然会做饭，即使你别的事一样也不会。be able to 也可以用，但不如can 用得经常。You are certainly able to cook .当要表达将来的能力时，一般要用will be able to Ill be able to speak German in another few months. 再过几个月我就会说德语了。（不能说：“I can speak ”）One day people will be able to run a kilometer in two minutes .总有一天人们会两分钟跑完一千米的。If I have a good sleep Ill be able to work out the problem.如果我睡个好觉，我就可以作出这个习题。但是，当人们现在决定将来是否有做某事的能力时，can 常常也是可以用的。Were too busy today ,but we can repair your car tomorrow .我们今天太忙了，但是明天我们可以给你修汽车。We can talk about that later . 这一点咱们以后再谈。Can you come to a party on Saturday ?星期六有个聚会，你能来吗？2、过去could 用来表达“一般的能力”即你过去想干什么就可以干什么。（was /were able to 也可以用来表达这个意思。）She could sing like an angel when she was a kid .当她还是个小孩子的时候，她可以唱得象天使一般好听。（也可以说she was able to sing ）My father could speak ten languages. 我父亲从前会说十种语言。不能用could 表达过去某种具体的能力（即在某一个场合做某事的能力），此时需要用 was able to , managed to , 或 succeeded in 等。How many eggs were you able to get ?你能弄到多少鸡蛋？（不能说：could you get ?）I managed to get 10% off the price .我弄了个九折。（不能说：“I could get ）After six hours climbing ,we succeeded in reaching the top of the mountain. 经过六小时的攀登，我们终于登上了山顶。（不能说：“we could reach ）（指成功地做成）试比较下列两个句子：he was a terrific liar :he could make anybody believe him .他说起谎来可神啦。能使任何人都相信他。（这里讲的是一般的能力，因此用could 是正确的。）I talked for a long time, and in the end I managed to make her believe me .我说了老半天，最后才使她相信了我的话。（这里指的是一个具体的场合，不能说：“I could make her ）但是要注意 could 的否定形式 couldnt 既用来表达一般的能力，也用来表达某一具体的能力。When I was younger I couldnt decide what I wanted to do. 我年轻些的时候，不能决定自己想要干什么。Simon was so drunk that he couldnt find the front door. 西蒙喝得烂醉，竟找不着正门在哪里。3、条件句中的couldcould 也用于条件句（意思等于 would be able to ）.I could have a really good time if I had a flat of my own. 要是我自己有一套房间，那我就可以过得很快活。We could do it by midday if we had the tools. 要是我们有工具的话，到中午就可以完成这件工作。I could break your neck ! 我可以掐断你的脖子。I could marry him if I wanted to (= I would be able to )要是我愿意，我就可以和他结婚。4、could 和动词不定式完成式连用有时候，我们需要表达我们有能力做某事件事，但是却没有去做。有一种特殊结构可以表达这个意思：could +不定式完成式（=could have +过去分词）。I could have married anybody I wanted to .(=I was able to marry anybody ，but I didnt .)我本来可以想跟谁结婚就跟谁结婚的。I could have killed her !(= I was so angry that I was capable of killing her , but I didnt .)我本来会宰了她的！You could have helped me !(=you were able to help me why didnt you? )你本来可以帮我一把嘛！这种结构也可用于条件句（意思等于 would have been able to ）.I could have won if I hadnt fallen over.(= I would have been able to win )要不是我摔了一跤，我本来是会赢的。这种结构如果用了否定形式，则表达“即使我尽力而为了，也还是未能做成”。I couldnt have won , so I didnt go in for the race 反正我也赢不了，所以我就没有参加赛跑I couldnt have enjoyed myself more - - it was perfect 我玩得没法再痛快了简直痛快极了。关于can 和could, may和might表示可能性的用法：*Will you answer the phone ? It can be your mother .*According to the radio it can rain this evening.这是两个错误的句子，为什么呢？can的用法与may和might 不同。我们用can来谈论更为一般性的或理论上的可能性，而不是某种实际上将要发生或正在发生的可能性。也就是说can通常不用来表示某种实际发生的可能性或真实性。当我们要表达发生某事的实际可能性时，我们用could（或may ,或 might）。因此上述两个句子中的can应当换成could ( may , might)。试比较:One can travel to Holland by boat ，by hovercraft or by air .到荷兰去，可以乘船，乘气垫船或乘飞机。I may fly to Amsterdam next week. 我也许下周坐飞机去阿姆斯特丹。我们不用can来表达某事将会发生的可能性，而是用may或might来表示。We may go climbing this summer .今年夏天我们可能会去登山。could 用来表达某事仅仅有发生的可能性，并不表示特别有可能发生。We could go climbing this summer , but I doubt if well have time.今年夏天我们可能去登山，但是我怀疑我们是否有时间去。It could rain later this evening. 晚上可能下雨。may 、 might和could也可以来表示在说话时某事可能是真实的。You may be right . 可能你是对的。You could be right ，but I dont think you are . 可能你是对的，但是我并不认为你是对的。This could be your big chance.这可能是你的大好机会。有时候，只在否定句和疑问句中，can 才用来表达现在可能性。Who can that be at the door ? 门外会是谁呢？Can it be Susan ? 会不会是苏姗呢？What can she possibly want？她可能要什么呢？It cant be true. 这不可能是真的。这里就不能说 *It can be Susan或*It can be true 这样的句子。请注意， cant这样用，意思与must相反。It cant be true. she must be mistaken. 这不可能是真的。她一定是弄错了。can及could与不定式完成式连用（have+过去分词）都表示对过去某事的猜测。can只能用于疑问句和否定句之中。Where can she have gone? 她会上哪儿去了呢？She cant have gone to schoolits Saturday. 她不可能是去上学了，今天是星期六。She could have gone off with some friends . 她可能是和几个朋友一起出去了。（不能说：*she can have）could 和不定式完成式连用也表示过去没有实现的可能性：某事可能发生，但是却没有发生。You were stupid to go skiing there you could have broken your leg . 你到那个地方去滑雪真傻，你可能会摔断腿的。It wasnt a good idea to throw the TV out of the window it could have hit somebody. 把电视机扔出窗外可不是个好法子可能会砸着人的。这种结构也可以用来批评某人没有完成某事。You could have told me you had invited people to dinner. (= why didnt you tell me ?)你本来可以告诉我你已请人来吃饭嘛？如果要表达某事过去不可能，我们可以用“couldnt have done”这种结构。My parents wanted me to be a doctor , but I couldnt have put up with all those years of study . 我父母亲原来想让我当医生，但是学习那么多年我可受不了。和could的用法一样，may和might也可以和不定式完成式连用，表示过去发生某事的可能性。Toms