祈使句(Imperative Sentence)表示请求，建议，命令，禁止等语气的句子 结构特点：1.省去主语；2.以动词原形开头 肯定祈使句/否定祈使句Sitdown./Don'tsit down. Comein./Don't come in. Eat quickly!/Don't eat quickly!
wear v.穿着：戴着（状态）接衣帽、饰物等 wear a skirt/hat/watch wear masks戴口罩 wear a smile面带微笑 put on穿上；戴上(动作) Put on your sweater!穿上你的毛衣！
Section A
important adj.重要的 it s important for sb.to do sth.做某事对某人来说是重要的 It's very important for us to wear masks now.现在戴口罩对我们来说是非常重要的。 importance n.重要性 the importance of health健康的重要性
quiet adj.形容词 安静的（修饰n.或放be/系动词后） quite adv.副词 很，非常(相当于very) be quiet/keep quiet/stay保持安静 We have to be/keep quiet in the library.在图书馆里我们必须保持安静
情态动词must表示“必须；务必 用法：主语+must+动词原形+其他例句：You must wear the school uniform at school
Section B
let型祈使句：let us+V原 sth
Section B
must和have to的比较 含义 否定形式及含义 用法 must 必须 mustn't 没有人称和数的变化，强调主观看法mus例如：You hust finish your homework today.He must go home now have to 必须,不得不 不必要don'thave to 例如：She has to go there now.右人称和数的变化，强调客观需要，You have to stay at home.
arrive后若是home，here，there等地点副词，则省略介词in/at
arrive at+小地方
arrive in+大地方
at+时间点
Section B
haveto表示“不得不“，必须”，强调客观需要 陈述句：主语+have/hasto+动词原形+其他 例句:We have to bequiet.She has to do her homework. -般疑问句：Do/Does+主语+have to+动词原形+其他 例句：Do you have to be quiet?Does she have to do her homework？
