Can/ Can/ could 的用法 can , could 能,会 (could 可以看作是 can 的过去式,这两个词除了时态不相同外,在表达意思的许多方 面是相同的。当然 could 也有自己独特的用法。) 1)表示脑力或体力上的能力 Nobody can stop the development of science . 谁也无法阻止科学的发展。 She can sing that song in English.她能用英文唱那歌。 He can submerge to a depth of about twenty meters . 他能潜入约二十米深的水中。 He could hardly support his family before he found the new job .他在找到那份 新工作前几乎无 法养家。 I could not understand the lecture on the computer given by Mr. Smith . 我听不懂史密斯先生作的那个关于计算机的讲座。 2)表示客观上的可能性 You can borrow this useful book from the library . 你可以从图书馆借到这种有用的书。 A more suitable person than him for the job can not be found . 不可能找到比 他更适合这份工作的人了。 Now people can skate on the lake .现在人们可以在湖上滑冰了。 When the storm stopped , the plane could take off . 当风暴停下来时,飞机可以起飞了不得。 3)表示主观上的允许 Can I ask you some questions about it ? 我可以问你有关这件事的几个问题吗? You can not leave here till I come back .直到我回来你才能离开。 Such kind of thing can't happen any more later . 这类事以后不准再发生了。 Can you tell me how to get to the airport ? 你能告诉我怎么去机场吗? Could you tell me how to get to the airport ? 您能告诉我怎么去机场吗? Could I be forgiven my negligence ? 请原谅我的疏忽,行吗? 4)(用于否定句、疑问句或感叹句中)表示猜测、怀疑或惊诧 How can / could you be here ? 你怎么会在这儿? She couldn't / can't be so stupid to do that . 她不可能蠢得去做那种事吧。 He couldn't / can't be over seventy .他不可能有七十多岁了。 Where could / can the boy be now ? 那孩子现在能在哪儿呢? 另外, could 还常用于表示较客气委婉的看法、 提问及用于虚拟语气的结构中。 这时候, could 就不可以看作是 can 的过去式了。而是 could 自己独特的用法。如: Could you speak a little slowly ? 您能稍微说慢一点儿吗? I'm afraid that we couldn't give you any definite answer at this moment . 恐怕我们这时候还无法给予您任何确切的答复。 I could come earlier if asked . 如果要让我早一点来,我可以来早一点。 We would appreciate it if you could offer us any help . 如果您能为我们提供帮助的话,我们将不甚感激。 You could have done better if you had worked harder at it . 如果你再加把劲,本来可以干得更好一些的。