1.祈使句 giving instructions
看例句，总结规律
Please come earlier next time.
Stop talking, please.
1）肯定祈使句：用动词原形开头，可通过please使命令的口气变得客气一点。
Please可放在句首，或放在句尾时，通常用逗号与句子的前面部分隔开。
2) 否定祈使句：用Don’t + 动词原形。
3）祈使句的反意疑问句
Put the book over there, will you?
Don’t leave your pet alone, will you ?
Let’s clean the fish tank, shall we ?
2.“must” &“should”
情态动词must意为“必须”,表示一种义务，主动去承担.否定mustn’t表示“不许可”,表示一种禁止.疑问式的否定回答常用 “needn’t”.
---Must I finish the work today?
---No,you needn’t.
情态动词should意为“应该”，否定形式为“shouldn't"意为“不该”，他们都用来向别人提出建议，告诉别人最好做哪些事或做那些事是正确的。
中考相关语法链接
1. Cars, buses and bikes _____ stop when the traffic light is red.
A. can B. must C. may D. need
2. --_____ I fill in the form now , sir?
--No, you needn’t. You can complete it this afternoon.
A. May B. should C. Must D. Would
3. _____ I have to show the school report to my parents, Miss King?
A. Must B. Do C. Can D. May
4. –Look ! Mr Hu is on the other side of the street.
-- It ______ be him. He has gone to Shanghai.
A. mustn’t B. can’t C. shouldn’t D. won’t
5. – Don’t play on the road again, will you?
-- ________.
A. Yes, I don’t. B. No, I won’t.
C. No, I will D. Yes, I won’t.
6. Let’s not pull its tail, shall we?（反意疑问句）