摘要:
**基本信息**
聚焦祈使句与情态动词(can/have to/must)的系统梳理,通过"规则表达三步法"和易错点判断构建方法体系,知识逻辑从基础结构到对比辨析层层递进,提升语言应用能力与思维品质。
**专项设计**
|模块|题量/典例|方法提炼|知识逻辑|
|----|-----------|----------|----------|
|语法总结|9大知识点|规则表达三步法(识别功能-检查结构-检查语气);易错点判断法(先功能后形式)|从祈使句基本结构→Let型→情态动词用法→must/have to对比,形成"概念-用法-辨析"递进链条|
|巩固练习|单选15/填空10/句型转换5/翻译5|单选考结构辨析,填空考词义辨析,句型转换考结构转换;典例覆盖must否定回答(needn't)等核心考法|从基础应用(单选/填空)到综合转换(句型/翻译),实现知识迁移与语言能力提升|
内容正文:
人教版英语七年级下册Unit2语法汇总与练习
祈使句与情态动词can、have to、must
第一部分 语法知识点总结
一、祈使句的基本特点
祈使句表示命令、请求、劝告、提醒或禁止,主语通常是听话人you,因此一般省略。肯定祈使句以动词原形开头。
结构:动词原形 + 其他。例:Keep the classroom clean. 加上please可以使语气更礼貌:Please close the door. / Close the door, please.
否定祈使句在动词原形前加Don't。例:Don't run in the hallways. 即使后面出现he或she等宾语,也不能把句首动词变为第三人称单数。
二、Let型祈使句
Let型祈使句常用“Let + 宾语 + 动词原形”提出建议或允许某人做某事。例:Let us help you. Let's是Let us的常用缩写,常表示“让我们……吧”。
Let's的否定形式常用Let's not + 动词原形。例:Let's not be late. 对Let's …的建议可以回答Good idea. 或Sorry, I can't。
三、情态动词can的用法
can可表示能力、许可或可能性,后接动词原形,没有人称和数的变化。例:We can play basketball after school.
否定形式为cannot或can't;一般疑问句把can提到主语前。例:Can we eat in the classroom? —No, you can't.
表示规则时,can常说明“可以做什么”,can't说明“不可以做什么”,语气通常比mustn't稍弱。
四、have to的用法
have to表示由于客观规定或外部情况而“不得不、必须”。主语为第三人称单数时用has to,后面仍接动词原形。
否定和疑问要借助do / does:don't have to、doesn't have to、Do … have to …?。例:She doesn't have to wear a uniform today.
don't have to表示“没有必要”,不是“禁止”。如果表示禁止,应使用mustn't或can't。
五、must的用法及与have to的区别
must表示说话人认为很有必要、规则要求或强烈命令,后接动词原形,也没有第三人称单数变化。例:Students must follow the school rules.
mustn't表示“禁止,绝不能”;must的一般疑问句把must提到主语前。肯定回答可用must,否定回答常用needn't或don't have to表示“不必”。
can / can't:可以 / 不可以,示例You can read here.
have to:受客观情况约束而必须,示例I have to leave now.
must:强烈要求或主观必要,示例You must be careful.
mustn't:禁止,示例You mustn't touch it.
六、祈使句表达不同语气
1、命令、请求与提醒
同样的动词原形结构可因语境表达不同语气。Stand up. 常是指令;Please help me. 是请求;Be careful. 是提醒。please、语调和场景共同决定礼貌程度。
2、be型祈使句
当表语是形容词或名词时,祈使句以be开头。例:Be quiet in the library. Don't be late again. 否定时仍在be前加Don't。
3、and / or连接的祈使句
“祈使句 + and + 陈述句”常表示做了前者就会有好结果;“祈使句 + or + 陈述句”常表示否则会有不良结果。例:Hurry up, or you will be late.
七、can的能力、许可与请求
1、表示能力
can表示现在具备的能力,如She can swim. 询问能力时使用Can …?,回答Yes, … can. / No, … can't. 动词形式不随主语改变。
2、表示许可
在规则语境中,You can … 表示允许,You can't … 表示不允许。can在这里不是说明能力,而是说明是否获得许可。
3、表示请求
Can you help me? 是日常请求。肯定回答可用Sure. / Of course.,拒绝时可礼貌说明原因。语法上仍是Can + 主语 + 动词原形。
八、must与have to的深层对比
1、说话人要求与客观需要
must常突出说话人的强烈要求或规则本身,have to常突出环境、时间或他人规定带来的必要。实际语境中二者有时都可表示“必须”,但强调角度不同。
2、人称和数的变化
must对所有主语形式相同;have to在一般现在时中随第三人称单数变为has to。否定、疑问也只有have to借助do / does。
3、否定意义不能互换
mustn't是“绝不能”,don't / doesn't have to是“不需要”。例:You mustn't enter. 表示禁止进入;You don't have to enter. 表示进入不是必要的。
九、规则表达的选择步骤
1、先识别交际功能
看句子是直接指令、询问许可、说明能力、强调必须、说明不必还是表示禁止。交际功能确定后,再选择祈使句或合适的情态结构。
2、再检查结构
祈使句和情态动词后都常出现动词原形,但have to的has变化不能遗漏。疑问句还要检查Can / Must是否提前,或Do / Does是否正确。
3、最后检查语气
在写建议或班规时,可使用please、can、must、mustn't等形成不同强度。避免整篇都使用强硬命令,让表达既准确又符合场景。
十、常见易错点与判断方法
看到规则语境时先判断是“允许”“必须”“不必”还是“禁止”,再选择can、must、have to等形式。
情态动词can、must后始终用动词原形;has to中只有have随主语变化,后面的实义动词仍用原形。
祈使句句首使用动词原形,否定式用Don't;不要把Don't have to和mustn't混为一谈。
第二部分 专项巩固练习题
一、单项选择(15题)
1. ____ late for class.
A. Not be B. Don't be C. Don't D. No be
2. —____ I take my pet dog into the library?
—Sorry, you ____.
A. Can; can't B. Must; can't C. Can; must D. Must; must
3. You ____ wear the school uniform today. It's the rule.
A. can B. have to C. can't D. don't have to
4. —Must I clean the classroom now?
—No, you ____. You can do it after school.
A. mustn't B. can't C. needn't D. shouldn't
5. ____ go out at night. It's dangerous.
A. Not B. Don't C. Doesn't D. Isn't
6. He ____ get up early because his home is far from school.
A. have to B. has to C. must to D. can to
7. —Let's ____ basketball after school.
—Good idea.
A. play B. to play C. playing D. plays
8. You ____ talk loudly in the reading room. It's the rule.
A. must B. mustn't C. can D. have to
9. Please ____ your homework before dinner.
A. finishes B. finish C. finishing D. to finish
10. You ____ buy any new books. We have many.
A. mustn't B. can't C. don't have to D. have to
11. Let's ____ be noisy in the hospital.
A. not B. don't C. doesn't D. no
12. —Can you swim?
—____
A. Yes, I can. B. Yes, I do. C. No, I can. D. No, I don't.
13. Hurry up, ____ you will miss the early bus.
A. and B. or C. but D. so
14. Students ____ follow the school rules.
A. must B. have C. can to D. must to
15. ____ quiet! The baby is sleeping.
A. Is B. Be C. Are D. Do
二、用can, can't, must, mustn't, have to, has to填空(10题)
1. You ____ smoke here. It is against the rule.
2. My mother is ill. I ____ go home now.
3. —____ I use your pen?
—Sure. Here you are.
4. Tom ____ wear glasses because his eyesight is poor.
5. You ____ finish your homework first before you watch TV.
6. You ____ take photos in this museum. Look at the sign.
7. I ____ get up early tomorrow. I don't have any classes.
8. ____ you play the piano?
9. We ____ be on time for class.
10. She ____ go to the party, because she has too much work.
三、句型转换(5题)
1. Eat in class.(改为否定祈使句)
____ ____ in class.
2. You have to wear sports shoes for P.E. class.(改为一般疑问句)
____ you ____ ____ wear sports shoes for P.E. class?
3. We must arrive at school on time.(改为同义句)
We ____ ____ arrive at school on time.
4. Let's play computer games.(改为否定句)
____ ____ ____ computer games.
5. You mustn't run in the hallways.(改为祈使句)
____ ____ in the hallways.
四、句子翻译(5题)
1. 请保持教室安静。
____________________________________
2. 你不必每天早起。
____________________________________
3. 我们必须遵守校规。
____________________________________
4. 快点,否则我们会迟到。
____________________________________
5. —我必须现在离开吗?—不,你不必。
____________________________________
第三部分 参考答案与解析
一、单项选择
1、B
解析:be型祈使句否定形式Don't be+形容词。
2、A
解析:can表示请求许可,否定回答用can't。
3、B
解析:客观规章制度要求,用have to。
4、C
解析:must引导一般疑问句,否定回答用needn't或don't have to,表示不必。
5、B
解析:实义动词开头祈使句,否定用Don't+动词原形。
6、B
解析:主语he三单,客观原因,用has to。
7、A
解析:Let's后接动词原形。
8、B
解析:mustn't表示禁止。
9、B
解析:please后接祈使句,用动词原形。
10、C
解析:don't have to 没有必要,不需要。
11、A
解析:Let's not do sth 让我们不要做某事。
12、A
解析:can引导一般疑问句,回答用can / can't。
13、B
解析:祈使句+or+陈述句,否则……。
14、A
解析:must情态动词,后接动词原形。
15、B
解析:be型祈使句,Be quiet保持安静。
二、用can, can't, must, mustn't, have to, has to填空
1、mustn't
2、have to
3、Can
4、has to
5、must
6、can't / mustn't
7、don't have to
8、Can
9、must
10、can't
三、句型转换
1、Don't eat
2、Do; have to
3、have to
4、Let's not play
5、Don't run
四、句子翻译
1、Please keep the classroom quiet.
2、You don't have to get up early every day.
3、We must follow the school rules.
4、Hurry up, or we will be late.
5、—Must I leave now? —No, you needn't.
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