cannot组成英语

一、cannot …too… "不可能把某事做过头；决不会…太"，与can never…too同义。e.g. One cannot be too much careful. "越小心越好。"二、cannot but + 动词原形，cannot help but + 动词原形，cannot help + 动名词，这三个短语在意义上基本相同，都表示"禁不住，不由得，不得不，不能不"的意思。cannot help + 动名词，是最规范的用法，最为常见。e.g. I cannot help admiring the picture whenever I look at it. "不管什么时候看到这幅画，我都禁不住要赞赏它。""cannot but + 动词原形"主要用于美国英语，用法不大规范。e.g. When the country calls you for help, you cannot but go. "当国家需要你的时候，你不能不挺身而出。""cannot help but + 动词原形"，这种用法多见于非正式文体。e.g. You cannot help but respect them. "你禁不住会尊敬他们。"三、can but + 动词原形，cannot but + 动词原形意思不同，但又不能把后者简单地理解为前者的否定。can but + 动词原形 = can only。e.g. I can but do my duty. "我只能尽我的职责。"而cannot but + 动词原形 = must; to be forced to do something。e.g. I cannot but go. "我必须走。"四、"cannot have done"，"could not have done"都可以表示以现在的眼光看来，"过去还可能发生的事"。e.g. They cannot/ could not have gone out because the light is on!但could not have done 还可以表示从过去某个时间点看来，"以前还可能发生的事。e.g. The girl asked to see a timetable, feeling sure that her father could not have made such a mistake.另外，cannot have done 要比could not have done 语气要强一些。还有一点值得注意：could not have done 有其相对应的肯定形式，即could have done。而cannot have done 却没有其相对应的肯定形式，即是说can have done 只能用在否定句和疑问句中。e.g.1) Where can he have gone?2) She's two hours late -- What can have happened?3) He can't have gone to Beijing --Just now I saw him.