情态动词有哪些?有什么区别?(初中部分)
情态动词有四类： ①只做情态动词：must,can(could),may(might),ought to ②可做情态动词又可做实义动词：need,dare ③可做情态动词又可做助动词：shall(should),will(would) ④具有情态动词特征：have(had,has) to,used to 情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前。
情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 not。
个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去，现在或将来。
情态动词属非及物动词，故没有被动语态。
助动词(auxiliary)主要有两类：基本助动词(primary auxiliary)和情态助动词(modal auxiliary)。
基本助动词有三个：do, have和be；情态助动词基本的有十四个：may, might; can, could; will, would; shall, should; must, need, dare, used to, ought to.had better 上述两类助动词的共同特征是，在协助主动词构成限定动词词组时，具有作用词的功能
情态动词和动词能一起出现在一个句子中吗
情态动词的否定形式：一、情态动词+not，以下为其缩写形式：can can't could couldn't would wouldn't should shouldn'tmay mayn't might mightn't need needn't must mustn'tdare daren't dared not ought oughtn't oughted not have(had, has) haven't (hadn't hasn't)shall shan't will won't二、情态动词+否定副词，如 never, impossibly 等。