05 助动词和情态动词 讲义--高三英语语法专题复习.docx

高中英语语法专题复习05 助动词和情态动词助动词实义动词本身往往无法独立表达某些语法概念，需要其他词的辅助。这类用来辅助实义动词构成谓语，但自身不能作为谓语动词的词，就是助动词(auxiliary verb)。英语中的助动词分为三类：1. 基本助动词 primary auxiliary2. 情态助动词 modal auxiliary3. 半助动词 semi-auxiliary基本助动词只有三个：be、do、have这三个词作为助动词使用时，本身没有实际含义。但这三个词也可以作为实义动词使用，需要注意区别这两种不同的动词身份。The rabbit has eaten a carrot.* 基本助动词have变位，辅助构成现在完成时态。The carrot was eaten by the rabbit.* 基本助动词be变位，辅助构成被动语态。The rabbit does like carrots.* 基本助动词do变位，辅助构成强调。The rabbit does not like carrots.* 基本助动词do变位，辅助构成否定。情态助动词共有14个，分别是：can/could, may/might, will/would,shall/should, must, ought to,dare/dared, need, used to情态助动词表示情态意义，其过去时形式并不一定表示过去时间。情态助动词不能独立用作谓语动词，只能和动词原形一起构成谓语。情态助动词的用法，将在后续详细介绍。半助动词在语法作用上介于主动词和助动词之间，包括：be able to, be going to, be about to, had better等等I'll be able to reach school on time if I leave right now.* 半助动词be able to，表示将来的能力。I was able to reach school on time because I left home early.* 半助动词be able to，表示过去的能力。You are to finish homework first.* 半助动词be to，表示被命令做某事。I think they're to fall in love with each other.* 半助动词be to，表示命中注定。You had better follow my orders.* 半助动词had better，表示最好做某事，有忠告、警告之意，暗含“如果不这么做，会有不好的后果”的意思。I'm going to eat dinner at 6PM today.* 半助动词be going to，表示将要做某事，并强调主观能动性，含有计划做某事的意思，而且通常是很快就要做某事。情态动词情态动词是助动词的一种，不能独立用作谓语动词，只能和动词原形一起构成谓语。情态动词本身有一定的词义，可以表达说话人的情感、态度和语气。常用的情态动词共有14个，分别是：can/could, may/might, will/would, shall/should, must, ought to, dare/dared, need, used to情态动词的用法分为非推测性用法和推测性用法。非推测性用法主要有以下几种：1. 表示能力 (can/could)He can drive a car.2. 表示请求、许可 (can/could, may/might, will/would, shall)Can/Could I borrow your book?May/Might I borrow your book?Will/Would you lend me that book?Shall we meet at 9AM？* 这里的过去时形式，与时间概念无关，表示更礼貌委婉的语气3. 表示义务、应当 (should, ought to, must)You should/ought to tell the police.You must finish your homework first.4. 构成将来时 (will/would, shall)The show will open on Friday.I shall never do that again.* shall表示将来，一般只用于第一人称5. 表示祝愿 (may)May you succeed！6. 表示命令、警告 (shall)You shall not frighten me out of this.7. 表示竟然 (should)It is strange that it should be so hot today.8. 表示需要 (need)You needn't worry about it.9. 表示敢于 (dare/dared)Tokyo dare not raise its interest rates again.10. 表示过去经常 (used to)We used to go sailing on the lake in summer.11. 表示禁止 (mustn't)You mustn't smoke here.* 注意mustn't 不是不必须的意思，而是必须不的意思，例如，Must I give you a thumbs-up?错误 No, you mustn't give me a thumbs-up.正确 No, you needn't give me a thumbs-up.正确 No, you don't have to give me a thumbs-up.* 这里的have to为半助动词。12. 构成虚拟语气，将在后续详细介绍情态动词的推测性用法，用来表示可能性，共涉及9个情态动词，分别是：can/could, may/might, will/would, should, ought to, must将其表达的可能性程序，从极其确定到极其不确定排序如下。通常，过去式形式表达的可能性都比原形低一些。must > will > would > ought to > should > can > could > may > mightIt will rain tomorrow. (明天会下雨)It can rain tomorrow. (明天可能会下雨)It may rain tomorrow. (明天也许会下雨)need和dare既能作情态动词，又能作实义动词，注意区别，1. 肯定句情态 She need stay at home today.实义 She needs to stay at home today.2. 否定句情态 She needn't stay at home today.实义 She doesn't need to stay at home today.3. 疑问句情态 Need she stay at home today？实义 Does she need to stay at home today？学科网（北京）股份有限公司