《英语写作--注意点》PPT课件.ppt

,Confusing shifits in number and person,情态动词无人称和数的变化 动词不定式没有人称和数的变化,情态动词有四类： 只做情态动词：must,can(could),may(might),ought to 可做情态动词又可做实义动词：need,dare 可做情态动词又可做助动词：shall(should),will(would) 具有情态动词特征：have(had) to,used to Example: 1.He/ I / we / could be here soon. 2.We/she/I cant carry the heavy box. 3. I would like to have read the article,need，dare作情态动词， 后接动词原形 need后加do， 否定形式为need not 例如： Need you go yet？ 你要走了吗？ Yes， I must. / No， I neednt.是的，我要走了/不，不急着 . 有人称和数的变化的是当它们作实意动词时， need to do sth, need doing sth, dare (not) to do sth 例如：He needs to go to school. You need looking care of yourself . She dares not to watch TV. 幻灯片 2,一般的情态动词没有人称和数的变化，而且所用的时态也受到一定的限制，而have to 有人称和数的变化。可用于多种时态中：一般现在时中当主语是第三人称单数时要用has to，其余的人称用have to，一般过去时中要用had to； 一般将来时中则要用will have to. e.g. She has to go to school by bus. 她不得不乘公汽上学。 Youll have to see the doctor if you get ill. 如果你生病了，就得去看医生。 幻灯片 1,不定式的基本形式: to动词原形,有时可以省略to 动词不定式的特点: 没有人称和数的变化,在句子中不能作谓语 Example （1）表示目的: The doctor came to operate on her. He has gone to town to do some shopping. I sat down to have a rest. He stopped to have a look. （2）表示结果: The girl cried only to make her mother angry. （3）表示程度: She is too tired to walk any farther. She is strong enough to carry the heavy box. （4）表示原因: I was surprised to read the news.,疑问词who,what,which,when,where,whether,how后可接不定式构成不定式短语，在句中作主语、宾语、表 语等。 When to leave for London has not been decided yet. （不定式在句子中做主语） Mr. Smith didnt know whether to leave or stay there. （不定式在句子中做宾语） I asked Professor Xu how to learn English well.