1、UNIT 2 Keeping Healthy,TOPIC 3 Must we exercise to prevent the flu?,Section C,Grammar Focus,1. 祈使句是表示请求、命令、叮嘱、号召、 劝告等的句子; 通常省略主语you; 句中谓语 动词用动词原形; 句尾一般用降调; 祈使句的 开头是动词原形。 祈使句有肯定和否定两种： e.g. Look out! 小心！Wait here for me! 在这等我！,Grammar,Come in, please! 请进！ Sit down, please. 请坐。 Lets go home. 我们回家吧。 否定的
2、祈使句是在动词前(即句首)加Dont. e.g. Dont talk in class! 不要在课常上讲话！ Dont open the window! 别开窗！ Dont be late for school. 上学别迟到 !Dont smoking! 别吸烟!,2. 情态动词have to 的用法,have to意思是“必须、不得不”, 它侧重于客观 上的必要和外界的权威。 1) 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; 句子是过去时, 用had to。) 如：,2) 否定形式: 主语dont have to动词原形 其他(一般现在时
3、, 主语是第三人称单数时, 用doesnt have to; 句子是过去时, 用 didnt have to) e.g. Nick doesnt have to wear a uniform.尼克不必穿制服。We didnt have to do our homework at once. 我们不必马上完成作业。,3) 疑问句: Do (Does 或 Did)主语have to 动词原形其他 如: -Do you have to stay at home on weekends? -Yes, I do. / No, I dont. 周末你必须呆在家里吗？是的, 我必须。/ 不, 我不必。 Di
4、d he have to go to bed by 11:00 last night? 昨晚, 他不得不11点前上床睡觉吗？,1) 表示能力, “会”, “能”(在第一册中已经学习 这种用法) 例如: Can you play the guitar? 你会弹吉它吗？ Judy can speak a little Chinese. 朱蒂会说一点中文。 I can dance and sing. 我能唱歌又能跳舞。,3. 情态动词can的用法,3) 表示允许、许可, “可以”、“能” (在这一课 中新学的词义) 例如: Can the students run in the hallways?
5、学生们可以在走廊上跑吗? We can eat outside. 我们可以在外面吃东西。 Can I come in? 我能进来吗?,注意: 同样是情态动词, can和have to的用法 是有区别的, 和大部分情态动词一样， can在否定句中, 直接在can后加上not， 在疑问句中, 把can放到主语前面， 并且没有人称和数的变化。,2. hear, listen和sound都有“听”的意思， 但三者是有区别的。 1) hear “听说”, 侧重于“听”的内容。例如: Im sorry to hear that you are ill. 听说你生病了, 我很难过。 I never hear
6、d such an interesting story. 我从来没听过这么有趣的一个故事。,2. What else do you have to do? else “其它的”, 用来修饰something, anything , nothing等, 还可用来修饰疑问词 what, where, who等, else修饰疑问词或不定代词时, 应后置。例如: Do you have anything else to do . Who else did you see?,1. Sit down.2. Come in.3. Eat at home.,Dont sit down.,Dont come
7、in.,Dont eat at home.,把下列祈使句改成否定句,4. Listen to music outside.5. Do your homework at school.,Dont listen to music outside.,Dont do your homework at school.,1. late, dont, for school, arrive2. music, listen to, in the classroom, dont3. eat, cant, in the classroom, we,Dont arrive late for school.,Dont
8、listen to music in the classroom.,We cant eat in the classroom.,Form sentences. 组句,4. sports shoes, you, wear, for, gym class, have to5. too, I, many, rules, have, in, my house,You have to wear sports shoes for gym class.,I have many rules in my house, too.,用can和cant填空,1. Mr Green _ smoke here, because theres a sign on the wall. It says “No smoking.” 2. Its very hot outside. You _ wear a hat. 3. We _ eat in the classroom, because its impolite to teachers. 4. I _ go to bed after 11:00 on school night. 5. The students _ read books and magazines in the library.,cant,can,can,can,cant,Thank you!,
