- 1 - 专题十一 情态动词和虚拟语气 情态动词 一、定义 情态动词表示说话人对某一动作或状态的态度。 二、特点 1．有一定词义； 2．不受主语人称和数的变化影响； 3．与主要动词的原形(或称不带 to 的不定式)一起构成谓语(除 ought to 作固定词组看待)。 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。 基本助动词与情态助动词最主要的区别之一是，基本助动词本身没有词义，而情态助动词则有自己的词义，能表示说话人对有关动作或状态的看法，或表示主观设想。 三、用法 1．can (could) Everyone here can speak English. (表能力) He can't / couldn't have seen her there. (表猜测) He could have gone home. (表猜测) Could / Can I use your pen? Yes, of course you can. (表允许) How can you be so careless? (表怀疑、惊异，主要用于否定、疑问句) Can / Could you lend me a hand? (表委婉发表观点) 2．may (might) You may take whatever you like.(表允许，证据更委婉) 注：在回答以 may引起的问句时，多避免用这个词，而用其他方式，如 Yes, please. / Certainly. / Please don't. / You'd better not. / No, you mustn't.等，以免显得太严谨或不客气。 They might be having a meeting, but I'm not sure. (表可能) 3．must - 2 - You must buy a ticket. (表义务，意为“必须” ) 注：回答Must...? 引出的问句时，肯定回答用must; 否定回答不能用mustn't, 而要用needn't或don't have to。 — Must I finish my homework now? — Yes, you must.(No, you needn't / don't have to.) This must be Lucy's. (表猜测，意为“想必；准是；一定” 等，用于肯定) “must have ＋ 过去分词” 表示“想必” 之意，表示对过去的事情的推测。 4．shall Shall I play soccer after supper? May I play soccer after supper? If you don't behave yourself, you shall be punished. 5．will I will do anything for you. ...
