情态动词助动词祈使句.pptVIP

Auxiliary Verbs  助动词 （be, have, do, shall, will） 本身无词义，不表示动作，不能单独作谓语，仅起辅助作用，与其它动词的一定形式一起构成谓语动词，或表示否定和疑问，或表示时态和语态,或表示加强语气等。 助动词在句中的作用: 1. 帮助构成谓语动词的否定式和疑问式： I don’t like your new hat. Is it raining now? Do you like my new hat? He has been learning English, hasn’t he? 2. 构成除一般现在时和一般过去时  之外的各种时态。 She is having a meeting. I shall help you any minute. I have been working in the company for years. Soon they would have reached their time limit and must return to the camp. 5.用来代替前面刚出现过的动词 或动词词组,以避免重复. Do you like English? --Yes, I do. He cooks as well as she does. I thought he’d come, but he didn’t. 6. 加强语气 He did know that. They think I didn’t read the passage, but I did read. Do come to the party tomorrow evening. 反义疑问句 陈述部分带有that 引导的从句时，附加疑 问部分一般应与主句谓语保持一致。但是 当主句陈述部分是I think, (I suppose, I believe)时，附加疑问句则要与从句谓语 保持一致。 It is the first time that she has been to Beijing,____? A. hadn’t she B. isn’t it C. has she D. is it I think she will be promoted, ____? A. don’t I B. won’t she C. do I D. will she They must have been here the day before yesterday, ? A. mustnt they B. didnt they C. mustnt have they D. had they 祈使句的反义疑问句： 1）在肯定的祈使句后，为了使祈使句听起来 比 较婉转，客气，可加一个简短的问句如will you，would you，can you，can’t you，could you的简短问句，使口气变得客气一些。如： ?? Open the window, will you? Be quiet, can’t you? 注意：否定式的祈使句后面只能用will you。 ???Don’t be nervous, will you? 2). 在Let‘s祈使句后加上 shall we ？ ( lets包含谈话的对方在内), 而在Let us （me ，her,…）后要加上 will you ？或won‘t you？ (Let us 不包括谈话的对方在内) 与be able to 的区别： can 只有现在和过去时态，强调能力； be able to有各种时态，表示“一时或经过努力的能力，强调结果。 Mary can play the piano .She has been able to play it since she was 5. Yesterday I was able to get home before the heavy rain. With the teacher’s help, I shall be able to speak English correctly. be able to 用于：　　 a. 位于助动