(共19张PPT)
单元语法复习
2021--2022学年第一学期期末考试英语复习
Unit 3 Safety
祈使句的构成、意义及运用
祈使句表示命令、请求、建议或劝告等。通常省略主语,谓语动词用原形,句末用感叹号或句号,读降调。
祈使句的结构
肯定祈使句的类型。
(1) Do 型( 即:行为动词+其他.)
e.g. Stand up, please. 请起立。
(2) Be 型( 即:Be +表语+其他.)
e.g. Be quiet, please. 请安静。
(3) Let 型( 即:Let +宾语+动词原形+其他.)
e.g. Let me help you. 让我帮助你。
______ noise pollution, and we can live in a quiet environment.
A. Prevent B. Preventing
C. Prevented D. To prevent
A
否定祈使句的类型。
(1) Don’t +动词原形+ 其他.
e.g. Don’t open the window. 不要开窗户。
Don’t be late. 别迟到。
______ walk on the grass.
A. Doesn’t
B. Don’t
C. Not
B
(2) Never +动词原形+ 其他.
e.g. Never give up! 千万不要放弃!
______ tell a lie.
A. Hardly B. Not
C. No D. Never
D
(3) No +名词/ 动名词. 多用于公共场合的提示语,意为“禁止……”。
e.g. No smoking!禁止吸烟!
No photos!禁止拍照!
祈使句的相关句型转换
“Let’s +动词原形.”结构,表示提建议,可与“Shall we +动词原形 ”或“Why not +动词原形 ”相互转换。
e.g. Let’s go fishing. = Shall we go fishing
= Why not go fishing
都表示提议“我们去钓鱼吧”。
“祈使句+ and/or +陈述句”可以转换为含if 引导的条件状语从句的复合句。
e.g. Hurry up, or you will be late.
快点,否则你会迟到。
= If you don’t hurry up, you will be late.
如果你不快点,你就会迟到的。
Tell him the truth at once, or he will be angry. (改为主从复合句)
_______ _______ don’t tell him the truth at once, he will be angry.
If you
语法专练
一、用括号内所给单词的正确形式填空
1. Danny, ________(be) careful with my vases.
2. ________(take) off your coat, Emily. It’s warm enough.
3. Don’t let any difficulty ________ (prevent) your dream from coming true.
be
Take
prevent
4. “Tom, don’t ________ (be) afraid of speaking in public. You are no longer a small boy,” said Mum.
5. ____________(remember) to cover your mouth when coughing.
be
Remember
二、单项选择
1. When I want to go out to play with my friends, my
mother always says, “_____at home. Don’t waste your time.”
A. Stay B. Stays C. To stay D. Staying
A
2. Please _____the rubbish into different litter bins according to the signs.
A. puts B. put C. putting D. to put
B
3. —Tony, don’t make so much noise! Your dad is sleeping now.
—Sorry, Mum, I _____.
A. will B. won’t C. do D. don’t
B
Bye-bye!