人教版初中英语七年级下册第四单元语法

人教版初中英语七年级下册第四单元语法
Unit 4单元语法小专题(Grammar Focus)
一、祈使句
1.定义
表示请求、命令、警告、建议等的句子叫祈使句。在祈使句中,一般以动词原形开头,通常省略主语you,句末可以用感叹号或句号。
2.祈使句的句式结构

祈使句句式 肯定形式 否定形式
P型:Please+动词原形+其他 Please stand up. Please don't stand up.
V型:动词原形+其他 Put away your things. Don't talk in class.
L型:Let+宾语+动词原形+其他 Let me help
you.
Don't let her go.
B型:Be+表语 Be careful Don't be late for class
N型:No+名词/动名词 / NO SMOKING

 3.祈使句的强调形式
为了指明向谁提出请求或命令,加强语气或表示感情色彩,也可以将祈使句的主语表示出来,以起强调作用。另外,祈使句的强调形式还可以在句首加do
You be quiet!你给我安静一会儿!
Do come earlier next time!下次一定要早点来!
二、musthave to的用法
1.两者均可表示“必须”,must更强调说话者的主观意愿,而have to强调客观上的必要性,意为“不得不”。
I must go nowor I will be late.我必须现在就走,否则就迟到了。
It's too late.I have to take a taxi.太晚了,我不得不乘出租车。
2must一般只表示现在,没有人称和数的变化,而have to则可以用于不同的时态,有人称及数的变化。
I/We/You/They must work hard./我们/()/他们必须努力工作。
She has to wear a uniform at school.她必须在学校穿校服。
3.两者的否定式含义大不相同。mustn't表示“不准;禁止”,而don't have to表示“不必”。
You mustn't swim in the river.你不准在河里游泳。
You don't have to get up early on weekends.周末你不必早起。
【注意】以must开头的一般疑问句,其肯定回答用must,否定回答用needn'tdon't have to
Must I go with you?我必须跟你们走吗?
Yesyou must./Noyou needn't/Noyou don't have to.是的,你必须。/不,你不必。

语法精练
.用括号内所给单词的适当形式填空。
1________(do) your homework right now(立刻)
2Please ________(be) quiet.
3____ ____(not let) the dog come in.
4No ________(swim)!
5They have to ________(do) their homework when they get home.
.单项选择。
(  )6.________ take the books out of the library.
ANot  BCan't
CDoesn't   DDon't
(  )7.________ dressed nowWe have to go in ten minutes.
OKMom.
AGetting  BGet
CTo get  DGets
(  )8.Students ________ wear school uniforms on weekdays.This is the rule of our school.
Acan   Bmay
Cmust  Dwill
(  )9.(绥化中考)Mummust I clean my room?
Noyou ________.
Amustn't  Bneedn't
Ccan't
(  )10.Annie's bike is broken()so she ________ walk to school.
Ahave to  Bhas to
Cneed to  Dhaving to