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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,情 态 动 词,一、什么是情态动词？,1.常见的情态动词有:,can , could , may , might , must ,need , have to , should 等.,2. 情态动词的否认式：,在情态动词后直接not,3 用法：,所有的情态动词后面都接动词原形.,Eg: I can swim .,He has to go now .,1. can表能力，可能性，允许，请求,Eg: 1. I can speak English well .,2. Anybody can make mistakes.,3. Can I go now,4. Can you lend me your bike,2. could 是can的过去式.表请求时，could 语气更委婉,3. be able to 表示能力 时态变化随意。将来时态用,be able to 来表示,二、情态动词的根本用法(一)、can 、could 和be able to 的用法,(二) may 和might 的用法,may,表示可能性,表示允许,表示祝愿,e.g. 1. She may be still waiting for us.,2. May I come in,3.May you have a happy holiday.,*,might是may的,过去式，语气更委婉。 但表示祝愿时不能用might.,(三)、must /have to 的用法,1. must ：表“必须.否认式，不需要neednt,- Must I hand in my exercises now,- Yes, you must. (No, you neednt.),2. mustnt : 表示“制止 You mustnt play in the street.,3. must ： 表示“猜测，只用于肯定句。,There must be a ticket left.,* 否认推测用，cant: You cant be hungry.,4. must + have + 过去分词： 对过去事实的肯定推测,You must have heard from her.,*,Must 的用法,*,have to的用法,must 与 have to,必须,1. must表示,主观意愿的必须,2. have to表示,客观需求,不得不,3. have to 比must,形式更多,e.g. He has to go now.,(,客观,),I must go now.,(,主观,),四need 和 dare 的用法,1. need “需要是情态动词，多用在否认 或疑问句中.,e.g. Need I attend the meeting tomorrow,You need not hand in the paper this week.,2. dare “敢，多用在否认或疑问句中。,e.g. The little girl dare not speak in public.,dare 当实义动词, dare to do,e.g. I dare to say it is not all done by yourself.,(五)、Will 和would 的用法,will (would) 表决心、愿望。,would 为 will 的过去式, 可用于各人称。,e.g. Ill do my best to catch up with them.,He said he would help me.,2. will, would用于疑问句表示说话人向对方提出请求或询问, 用 would 比 will 更婉转,客气。,e.g. Will you help me to work it out,Would you like some coffee？,有时will 和would 也可以表猜测,e.g. There will be a postman at the door.,Id say shes about 40.,六、should /ought to的用法,2. ought to “应当；应该。和should 差不多，只是口气较重,否认式： ought not to,e.g. You ought to bring the child here. (应该),You ought not to have cut away the trees,1. Should 表示劝告，建议，作“应该讲。,1. After that, you should list your work exercises.,2. You shouldnt feel unhappy.,三、Exercises:,见课本P62,Grammar Focus,1. Complete the following sentences by using a suitable modal verb.,
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