(
课件网) Don’t eat in class. Unit 4 Section A Grammar Focus-3c e.g.我们必须准时。 We must be on time. 我们不得不穿校服。 We have to wear the school uniform. 我们不能在教室里跑。 We can’t run in the classroom. 主语+must+V原 主语+have to+V原 主语+can't+V原 如何使用情态动词表达规矩？ Grammar Focus. must 作为情态动词，表示“_____”。强调说话人的主观看法，语气比较强烈。 例如:你明天务必要来。 You ____ come tomorrow. 注：在回答must引起的问句时，如果是否定的答复,用don’t have to或needn’t (不必) , 但不能用mustn’t (不允许, 禁止) 。 must Grammar Focus. 必须，务必 must Must I finish the homework? No,_____. you needn't./you don't have to. have to意思是“必须，不得不”，侧重于客观上的 必要。 结构: 主语＋have?to＋动词原形＋其他 (一般现在时) 主语是第三人称单数时, 用has?to； 如： 他们不得不在放学后打扫教室。 They _____ clean the classroom after school. 汤姆每天必须练习弹吉他。 Tom?_____?practice?the?guitar?every?day.? have to Grammar Focus. have to has to 2) 否定形式: 主语＋don’t?have?to＋动词原形＋其他(一般现在时) 主语是第三人称单数时, 用doesn’t?have?to（“不必”）; Nick?_____?wear?a?uniform.尼克不必穿制服。 You?_____be here before 7:00.? 你不必在上午七点前到这。 3) 疑问句: Do(Does)＋主语＋have?to?＋动词原形＋其他？ 如: —Do?you?have?to?stay?at?home?on?weekends?? 周末你必须待在家里吗？ —Yes,?I?do.?/?No,?I?don't.?是的，我必须。/ 不， 我不必。 Grammar Focus. doesn't have to don't have to 把下面的句子改为一般疑问句 1. I must clean the bedroom every day. Must you clean the bedroom every day? 2. He has to look after his little brother. Does he have to look after his little brother? 练一练：用have to, must 填空 1. It’s cold outside. We _____ stay at home. 2. We ____ be good with our parents. 3.I _____ study hard(努力学习). 4.Mother is out, so I _____ look after my little sister. have to must must have to Read through Grammar Focus, then fill in the blanks: 1)祈使句的否定句在_____前加_____, 表示“不要做什么事”。祈使句的肯定句通常是以_____开头。 2)情态动词can, must, have to后接动词___形。 3)从表格内包含can的句子可以看出can 的意思是“_____, _____”，与前面can 表示“____”不同。 4)Have to 与其他情态动词用法不同，有_____和_____的变化。 动词原形 Don’t 动词原形 原 能够 允许 能力 人称 单复数 读以下句子并将其分类，给出分类的理由。 1.Open the door, please. 2.Be a good boy! 3.Come and buy our clothes. 4.Let him try. 5.No smoking! 6.Let’s walk to school. 7.No photos. 8.Let me tell you my school life. 9.Be quiet in the library. 答案：1, 3, 2,9 4，6，8 5，7 1.Open the door, please. 3.Come and buy our clothes. 2.Be a good boy! 9.Be quiet in the library. 4.Let him try. 6.Let’s walk to school. 8.Let me tell you my school life. 5.No smoking! 7.No photos. Do 型 Be型 Let型 No型 1. 肯定祈使句的常见句型结构： (1) Do型：动词原形+宾语+其他. 如： Open the door, please. (2)Be型：Be+表语. 如：Be a good boy! (3) Let型：Let+宾语+动词原形+其他. (或：Let’s+动词原形+其他.) 如： Let me help you. 又如：Let’s play tennis. 2. 否定祈使 ... ...
