学习必备欢迎下载助 动 词[学习目标 ] 掌握助动词的基本用法[知识点总结 ] 一、定义助动词是英语特有的一类词， 它们本身一般没有词义， 不能单独作谓语。 其作用在于帮助实义动词构成谓语，表示时态、语态、语气等，构成疑问及否定形式。有以下几种： be(am, is, are, was, were, being, been), have(has, had, having), do(does, did), shall(should), will(would) 。二、用法1、助动词 be(am, is, are, was, were, being, been) (1) be 后跟现在分词构成进行时态Who is playing the piano? 谁在弹钢琴？She was reading a book then. 那时她正在读书。(2) be 后跟过去分词构成被动语态He was asked to do the work. 有人要他干这件工作。(3) be 后跟动词不定式构成谓语：a. 表示计划、安排将要发生的事。They were to leave the following day. 他们将在第二天动身。b. 肯定形式表示指示、命令，而否定形式表示禁止。You are to see the headmaster today. 今天你必须去见校长。Anybody is not to enter the room without permission. 未经允许任何人不能进入房间。c. 表示义务、责任等，相当于should。You are to be back before 5. 你得在 5 点钟以前回来。d. 表示可能性，与情态动词may, can 同义。Such books are to be found in any library. 这种书在任何图书馆都有。2、助动词 have(has, had, having) (1) 助动词 have 可以构成完成时或完成进行时English has been taught in China for many years. 中国教英语已经多年。I have been studying English for 10 years. 我一直在学英语，已达十年之久。(2) 和动词不定式构成谓语，表示客观上不得不做的事情We’ ve missed the train. We’ ll have to wait for another one.我们已经误了火车，只能等下一辆了。3、助动词 do(does, did) (1) 构成疑问句或否定句How did you know about it? 你是怎么知道这件事的？He likes music, doesn’t he? 他喜欢音乐，对吧？(2) 用来加强语气Do come and see us. 一定要来看我们。(3) 代替前面刚出现的动词，避免重复He speaks English as fluently as she does. 他英语讲得和她一样流利。学习必备欢迎下载(4) 用于倒装句Never did I hear of such a thing. ...
