2017年秋季课程外研版初二英语
第17讲：语法回顾—情态动词和祈使句 (120分钟)
一、课程介绍
知识点
1. 情态动词的基本用法 2. 情态动词表示推测的用法 3. 情态动词的肯定回答和否定回答 4. 掌握祈使句的构成 5. 掌握祈使句的否定回答
教学重点
1. 情态动词的肯定回答和否定回答 2. 情态动词表示推测的用法
教学难点
1. 情态动词的肯定回答和否定回答 2. 情态动词表示推测的用法
二、要点回顾
Ⅰ.知识回顾
用a或an填空：
1. ____ honest boy 2. ____ ugly man 3. ____ useful tool 5. ____ uncle 9. ____ umbrella 13. ______ ―h‖ 【答案】
an; an; a; an; an; a; a; an; an; an; an; an; an; a
6. ____ uniform
7. ____ university
4. ____ one-act play 8. _____ hour
12. ______ ―s‖
10. _____ interesting story 14. ______ ―u‖
11. _____ ―x‖
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Ⅱ.活用句型
Most new people were born in developing countries. These countries are found in much of Africa, South America and some parts of Asia. In the developed countries of Europe and North America, the population is growing very slowly. This is because women in these countries have,on average(平均),only one or two children. In the developing countries, many women have five or more children. In 1950,around__________①(百分之二十五)of the world’s population lived in the developed countries. By 2050, these countries will be home to only around one tenth of the world’s population.
②In the developing countries, more than one billion people are still living below the poverty(贫困)line. These people do not have enough food to eat and they live in poor housing. Children get little time at school and people suffer(遭受痛苦)from many kinds of diseases.
③At the beginning of the 21st century, the world’s population was around six billion. The U.N. has said that the world’s population will level off(平稳下降)at 12.5 billion by the year 2100. Other groups think the world’s population will continue to grow, reaching 14 billion before it becomes stable(稳定的),or even falls. 阅读短文,完成下列任务。
1.In what areas of the world can developing countries be found?
__________________________________________________________________ 2.将①处的汉语翻译成英语。
__________________________________________________________________ 3.将句②翻译成汉语。
__________________________________________________________________ 4.写出句③的同义句。
At the beginning of the 21st century, the world______ ______ ______ ______about six billion. 5.There will be twelve and a half billion people on the earth in 2100,won’t there? __________________________________________________________________ 【答案】
1.In much of Africa, South America and some parts of Asia. 2.twenty-five percent
3.在发展中国家,超过10亿的人仍然生活在贫困线以下。 4.had a population of 5.Yes, there will.
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三、知识精要
语法知识列表
【语法点一】情态动词can和could的用法 【语法点二】情态动词may和might的用法 【语法点三】情态动词need的用法 【语法点四】情态动词must的用法 【语法点五】祈使句的用法
四、要点讲练
【要点1】can的用法
⑴ 表示体力或智力上的能力，即“能够，会”，可与be able to转换。 例：He can speak English. = He is able to speak English. —Can you play basketball? — No, I can’t.
如果表示将来具备的能力，要用will be able to。 例：If I have a good sleep, I will be able to do the problem. ⑵ 表示许可，主要用于口语，书面语一般用may。 例：—Can we go home now, please? — No, you can’t.
You can only smoke in this room.
You can’t keep the library books for more than a month.
⑶ 表示“可能”，用于表示推测，与may同义，但一般用在否定句和疑问句中。 例：What can he possibly want?
在否定句中，否定形式can’t表示推测“不大可能”。 例：Anybody can make mistakes. The news can’t be true.
与第一、二人称连用时，还可以就可能的解决问题的方式或可能的行为提出建议。在这里，也可用could使语气婉转。 例：Can / Could we meet again next week? 下周我们可以再见面吗？ —What shall we do? 我们怎么办呢？
— We can / could try asking Lucy for help. ——我们可以请露茜帮忙试试看。 You can / could help me with the cooking. 你可以帮我做饭。
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【例题】
-Can you speak Japanese? -No, I____.
A. mustn't B. can't C. needn't D. may not 【解析】
考查can的肯定回答和否定回答 【答案】B
【即学即用】
---He___ be in the classroom, I think.
---No, he ___ be in the classroom. I saw him go home a minute ago. A. can; may not B. must; may not C. may; can't D. may; mustn't 【答案】C
【要点2】 may的基本用法: ⑴ 表示“许可”，用can比较口语化。
例：You may / can come if you wish. 如果你想来，你就来。 You may not pick flowers in this park. 本公园内不许摘花。
（may not表示按规定不许可，如果用mustn’t则表示说话人不许可。） —May I smoke here? 我可以在这里抽烟吗？
—No, you mustn’t. 不行。（mustn’t表示明确的禁止。） ⑵ 肯定句中表示推测，“可能”。
例：It may rain tomorrow. 明天可能会下雨。 The news may not be true. 这个消息可能不会是真的。 注意：如果在疑问句中表示“可能”，通常用can。 例：Can it be true? 那会是真的吗？ Who can he be? 他究竟是谁呢？ ⑶ 【注意】：—May I/we……？ 【例题】
—May I watch TV for a while？
—No, you _______. You have to finish your homework first.
A. shouldn’t B. needn’t C. mustn’t D. won’t 【解析】
考查may/might 的肯定回答和否定回答。
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