2020中考英语语法专题十 情态动词（专项练习）（解析版）

2020中考英语语法专题十 情态动词（专项练习）情态动词
一基本用法
1.(2018北京）I _________go now, or I'll miss my train.
A . can B . might C . must D . could
2.(2018上海）——Must I do the project on my own?
-No, you ________ . You can work with your classmates .
A . needn't B . can't C . shouldn't D . mustn't
3.(2018安徽）——May I watch TV, Dad?
-When your homework is finished , you _________ .
A. should B. can C. must D. need
4.(2018重庆B卷）You ________stop when the traffic lights turn red.
A. can't B. may C. must D. needn't
5.(2018连云港）——How amazing this robot is!
-Wow, it has video cameras in its eyes, so it _________"see" and interact with people.
A. may B. can C. must D. should
6.Hi, class ! You _________come to school tomorrow .
——Wow, great news!
A. wasn't able to B. won't have to C. shouldn't D. mustn't
7.(2018盐城）Look, little Jim is swimming so fast .I ________believe my eyes.
A. shouldn't B. can't C. mustn't D. needn't
8.(2018白银）——Can we play soccer here?
-No, you _______ play it near the road . That’s too dangerous !
A. can B. may C. won't D. mustn't
9.(2018资阳）— __________I have a talk with you now?
—Sorry, I'm quite busy.
A. Will B. Must C. May D. Need
10.(2018凉山州）Parents ______put the things like knives and medicine away in the house to keep children safe.
may B. might C. can D. should
二 表推测
1.(2018河南）-Are you going to the cinema tonight?
- I don't know . I ________ go or I ________ stay a home .
A. will; will B. must; must C .should; should D. might; might
2.(2018成都）—Wow...another gift! What's in the box?
-I'm not sure . It ______ be a pair of sports shoes .
A. must B. may C. will
3.(2018青岛）This book ________be Lucy's. Look! Her name is on it.
A. can B. may C. must D. might
4.(2018达州）—Look! The woman at the school gate __________ be our headmaster .
——No, it ______ be her . She is holding a meeting in the office now .
must; can't B. must; mustn't C. can; needn't D. may; mustn't
5.(2018长沙）——Is the man over there Adam?
-It _______ be him . He has gone to Hong Kong on vacation .
A. must B. can't C. mustn't
6.(2018盘锦）-Have you made a plan for this summer vacation
-Well, not yet. I _______ go to Thailand with my family.
A. may B. can C. must D. a
分类真题
1.(2019天津，27)You _______walk on the wet hill path because you ________ fall and hurt yourself.
A. must; might not B. mustn't; might C. needn't; need D. must; must
2.(2019四川成都，32)-Is that Tom over there?
—— It _______ be him . He is on the plane to Chengdu now .
A . can't B . might not C . must
3. David , ________ please sweep the floor and take out the trash?
A. could B. may C. might D. must
4.(2019湖北武汉，35)—Try this soup-you _______ like it.
——Wow! This is delicious!
A. must B. will C. shall D. can
5.(2019黑龙江齐齐哈尔，5)—The summer vacation is coming. Have you made a plan for it?
——Not yet. I _______go to Guilin .
A. may B. can C. should
6.(2019河南，31)Jerry didn't pay me back, but he promised that he ______ this Sunday .
A. must B. could C. would D. should
7.(2019江苏苏州，4)—Some people don't show their talents at the very beginning.
-I agree. Even Einstein _______ read until he was seven .
A. can't B. mustn't C. couldn't D. needn't
8.(2019广东，42)Dirty air and water are harmful. They ________kill plants, and even people.
A. can B. can't C. should D. shouldn't
9.(2019北京，4)-Lily, ____you finish the letter in ten minutes?
-Yes, I can.
A. must B. should C. need D. can
10.(2019山东青岛，3)As middle school students, we _______ follow the public rules wherever we go.
A. would B. should C. might D. could
11.(2018四川成都，34)—Wow...another gift! What's in the box?
-I'm not sure . It _______ be a pair of sports shoes .
A. must B. may C. will
12.(2018湖北武汉，35)-Must you go?
-Yes , I'm afraid I really _______ ,
A. may B. should C. must D. can
13.(2018内蒙古包头，26)-Excuse me, where is the nearest bank ?
-Go straight ahead ; you ______ miss it .
A. mustn't B. can't C. needn't D. shouldn't
14.(2018上海，34)——Must I do the project on my own?
- No , you ______ . You can work with your classmates .
A. needn't B . can't C. shouldn't D. mustn't
15.(2018云南，29)——Will you go camping with us, Bob?
- I'd love to , but I ______ study for the test .
A. may B. must C. can D. could
16.(2018湖北黄冈，29)-Must I finish reading the book today, Mr. Brown?
No, you _______ . You can finish it in two days .
A. needn't B. mustn't C. can't D. couldn't
17.(2017北京，25)——— ______ I hand in the report today?
-No, you needn't.
A. Can B. Must C. Shall D. Could
18.(2017上海，41)———— _________I park my car here for a while?
-No, you mustn't. Do you see the sign "NO PARKING"?
A. Would B. May C. Must D. Should
19.(2017重庆，26)——May I take the dog with me, sir?
_______ . Pets are not allowed to enter the hall .
A. Yes, you may B. No, you mustn't C. Yes, you can D. No, you needn't
20.(2017河南，28)——I don't care what people think.
----Well , you _______ .You’re not alone in this world .
A. can B. may C. should D. will
21.(2017湖北武汉，35)—Have you got the results of the exam?
-No. All we _________ do now is to wait.
A. must B. can C. may D. could
22.(2017天津，37)When you are travelling, bring a map because it _________ help you.
A. can't B. mustn't C. used to D. may
23.(2017黑龙江哈尔滨，14)-Must I prepare for the trip today?
——No, you ______prepare for it today . You can do it tomorrow.
A. need B. don't need C. needn't
24.(2017四川成都，36)This pair of glasses _________be Tony's. He's the only one who wears glasses.
A. must .B. might C. can't
25.(2016山西，20)-Many people play with mobile phones all day instead of reading books.
——That's too bad . Everyone _________ be a book lover .Reading is more enjoyable.
A. may B. should C. would
26.(2016天津，37)——Mum,____________ I play football this afternoon?
-Sure, but you _______ finish your homework first.
A. may; could B. can; must C. can; mustn't D. may; can't
27.(2016黑龙江哈尔滨，7)—Hi, Jack! Could you come to our English party ?
-Sorry, I_______.I have to look after my little sister at home.
A. must B. could C. can't
28.(2016重庆，28)——Must we finish the work today?
A. Yes, we can B. No, we can't C. Yes, we must D. No, we needn't
29.(2016宁夏，24)-Can I go swimming, Mom?
——Certainly . But you _________ be back by four .
A. can B. may C. might D. must
30.(2016福建福州，25)—Look at the young lady in red. Is it Mrs. Li?
——No. It be her. She is wearing a white dress today.
mustn't B. needn't C. can't
2020中考英语语法专题十 情态动词（专项练习）情态动词
一基本用法
1.(2018北京）I _________go now, or I'll miss my train.
A . can B . might C . must D . could
【答案】C
【解析】考查情态动词的基本用法。句意为：我___现在走，否则我会错过火车。can能，会；might也许；must必须；could能。结合语境可知此处为我必须现在走，否则会错过火车。故选C。
2.(2018上海）——Must I do the project on my own?
-No, you ________ . You can work with your classmates .
A . needn't B . can't C . shouldn't D . mustn't
【答案】A
【解析】考查情态动词的基本用法。句意为“我必须自己做这个项目吗？”“不，你——，你可以和你的同学合作。”用情态动词must来提问，否定回答时使用needn't。故选A。
3.(2018安徽）——May I watch TV, Dad?
-When your homework is finished , you _________ .
A. should B. can C. must D. need
【答案】B
【解析】考查情态动词的基本用法。句意“爸爸，我可以看电视吗？”“当你完成了作业，你就——。”should应该；can可以；must必须；need需要。根据句意可知此处表示许可。故选B。
4.(2018重庆B卷）You ________stop when the traffic lights turn red.
A. can't B. may C. must D. needn't
【答案】C
【解析】考查情态动词的基本用法。句意：当交通灯变红时，你——停下。can't不能；may可能；must必须；needn't 不必。根据常识红灯亮时，必须停下，故选C
5.(2018连云港）——How amazing this robot is!
-Wow, it has video cameras in its eyes, so it _________"see" and interact with people.
A. may B. can C. must D. should
【答案】B
【解析】考查情态动词的基本用法。句意为“这个机器人真是棒极了！”“哇，它的眼睛里有摄像头，所以它'看'并和人互动。"may也许，可能；can可以，能够；must必须；should应该，应当。由句意可知，机器人拥有能够看见的能力。故选B。
6.Hi, class ! You _________come to school tomorrow .
——Wow, great news!
A. wasn't able to B. won't have to C. shouldn't D. mustn't
【答案】B
【解析】考查情态动词的基本用法。句意“嗨，同学们！
你们明天______来学校了。""哇，好消息！"wasn't able to不能；won't have to不必；shouldn't不应该；mustn't禁止。根据答语中“great news”可知是不必来学校，故选B。
7.(2018盐城）Look, little Jim is swimming so fast .I ________believe my eyes.
A. shouldn't B. can't C. mustn't D. needn't
【答案】B
【解析】考查情态动词的基本用法。句意为：看，小吉姆游得如此快。我_____相信我的眼睛。shouldn't 不应该；can't不能；mustn't禁止；needn't不必要。根据句意，表示我不能相信我的眼睛。故选B。
8.(2018白银）——Can we play soccer here?
-No, you _______ play it near the road . That’s too dangerous !
A. can B. may C. won't D. mustn't
【答案】D
【解析】考查情态动词的基本用法。句意为“我们可以在这里踢足球吗？”“不，你——在路边踢足球。那太危险了！”can可以，能够；may或许，可能；won't不会；mustn't不准，禁止。根据句意可知此处表禁止。故选D。
9.(2018资阳）— __________I have a talk with you now?
—Sorry, I'm quite busy.
A. Will B. Must C. May D. Need
【答案】C
【解析】考查情态动词的基本用法。句意为“我现在和你谈谈吗？”“抱歉，我现在相当得忙。”will将，愿意；must必须；may可能，也许，可以；need需要。结合语境可知此处为委婉征求是否可以谈一谈，结合四个选项可知C项符合语境。故选C。
10.(2018凉山州）Parents ______put the things like knives and medicine away in the house to keep children safe.
may B. might C. can D. should
【答案】D
【解析】考查情态动词的基本用法。句意为：在家里父母——把刀和药之类的东西收起来以保证孩子的安
全。may可以；might或许；can能；should应该。根据语境可知此处指应该把刀和药之类的东西收起来。故选D。
二 表推测
1.(2018河南）-Are you going to the cinema tonight?
- I don't know . I ________ go or I ________ stay a home .
A. will; will B. must; must C .should; should D. might; might
【答案】D
【解析】考查情态动词表推测。句意“今晚你去看电影吗？”“我不知道，我——去或者我_____待在家。"will将会；must一定；should应该；might可能。根据答语中的“I don't know."可知并不确定今晚做什么，因此用might表示可能性较小的肯定猜测。故选D。
2.(2018成都）—Wow...another gift! What's in the box?
-I'm not sure . It ______ be a pair of sports shoes .
A. must B. may C. will
【答案】B
【解析】考查情态动词表推测。句意“天哪，还有另外一个礼物，盒子里是什么呢？”“我不确定，它——是一双运动鞋。”must必须；may可能；will将会。根据前句“不确定”可知选B。
3.(2018青岛）This book ________be Lucy's. Look! Her name is on it.
A. can B. may C. must D. might
【答案】C
【解析】考查情态动词表推测。句意为：这本书
是露西的。看！上面写着她的名字。can能；may可能；must一定；might可能。根据“Her name is on it.”可知这本书一定是露西的。故选C。
4.(2018达州）—Look! The woman at the school gate __________ be our headmaster .
——No, it ______ be her . She is holding a meeting in the office now .
must; can't B. must; mustn't C. can; needn't D. may; mustn't
【答案】A
【解析】考查情态动词表推测。句意为“看！学校门前的那位女士——是我们的校长。”“不，那——是
她。她现在正在办公室里主持一个会议。”must一定，必须，表示强烈的肯定推测；can't不能，不会，表示强烈的否定推测；mustn't禁止；can能，会；needn't不需要；may可能。根据"She is holding a meeting in the office now."可知那个人一定不是我们的校长，所以第二空应用can't表示强烈的否定推测。故选A
5.(2018长沙）——Is the man over there Adam?
-It _______ be him . He has gone to Hong Kong on vacation .
A. must B. can't C. mustn't
【答案】B
【解析】考查情态动词表推测。句意“那边的那个人是亚当吗？”“那——他，他已经去香港度假了。”must必须；can't不可能，表示否定推测；mustn't禁止。根据他去香港度假可知此处指他不可能是亚当。故选B
6.(2018盘锦）-Have you made a plan for this summer vacation
-Well, not yet. I _______ go to Thailand with my family.
A. may B. can C. must D. a
【答案】A
【解析】考查情态动词表推测。句意“为这个暑假你制定好计划了吗？”“还没有。我——和我的家人去泰国。”根据“Well,not yet.”可知此处表示可能去泰国。故选A
分类真题
1.(2019天津，27)You _______walk on the wet hill path because you ________ fall and hurt yourself.
A. must; might not B. mustn't; might C. needn't; need D. must; must
【答案】B
【解析】句意：你千万别在潮湿的山路上走，因为你可能会跌倒并且伤到自己。本题考查情态动词的用法。第一个空表示“禁止，不允许”，第二个空表示“可能”，故本题选择B。
2.(2019四川成都，32)-Is that Tom over there?
—— It _______ be him . He is on the plane to Chengdu now .
A . can't B . might not C . must
【答案】A
【解析】句意：——那边的是Tom吗？——不可能是他。他现在正在去往成都的飞机上。本题考查情态动词表示推测的用法。由答语中“He is on the plane to Chengdu now.”可知，说话人十分确定那边的那个人不可能是Tom,故选择A。
解题技巧 情态动词表推测的试题的解题关键是找到表明说话人确定或不确定的句子，如本题答语中的“He is on the plane to Chengdu now.”，可推测说话人十分确定那边的那个人不是汤姆。
3. David , ________ please sweep the floor and take out the trash?
A. could B. may C. might D. must
【答案】A
【解析】句意：戴维，请扫扫地并且把垃圾带出去好吗？本题考查情态动词。could能，可以（礼貌地请求别人做某事）;may也许，可能；might可以；must必须。根据句意可知应是客气地提出请求，故选A。
4.(2019湖北武汉，35)—Try this soup-you _______ like it.
——Wow! This is delicious!
A. must B. will C. shall D. can
【答案】B
【解析】句意：——尝一尝这个汤，你会喜欢的。——哇！这个很好喝！本题考查情态动词。A:必须；B:会；C:应该；D:能，可以。根据答句中“这个很好喝”可知此处应该表达“你会喜欢的”，故本题选择B。
5.(2019黑龙江齐齐哈尔，5)—The summer vacation is coming. Have you made a plan for it?
——Not yet. I _______go to Guilin .
A. may B. can C. should
【答案】A
【解析】句意：——暑假就要到了。你制订计划了吗？——还没有。
我可能去桂林。本题考查情态动词。根据答语中Not yet可知，说话人还没有计划，所以“去桂林”也只是一种可能，故选A。
6.(2019河南，31)Jerry didn't pay me back, but he promised that he ______ this Sunday .
A. must B. could C. would D. should
【答案】C
【解析】句意：杰里没有把钱还给我，但是他许诺本周日还我。本题考查情态动词的用法。A.必须；B.可以；C.会，将会；D.应该。根据he promised及时间状语 this Sunday可知宾语从句的时态为过去将来时，故选C项。
7.(2019江苏苏州，4)—Some people don't show their talents at the very beginning.
-I agree. Even Einstein _______ read until he was seven .
A. can't B. mustn't C. couldn't D. needn't
【答案】C
【解析】句意：——有些人在一开始时没表现出他们的天赋。——我同意。即使爱因斯坦也是到他7岁时才能阅读。本题考查情态动词。can't不能；mustn't禁止；couldn't不能，can't的过去式；needn't不需要。根据until引导的时间状语从句中的时态可知，应用一般过去时，故选C项。
8.(2019广东，42)Dirty air and water are harmful. They ________kill plants, and even people.
A. can B. can't C. should D. shouldn't
【答案】A
【解析】句意：肮脏的空气和水是有害的。它们能杀死植物甚至人。本题考查情态动词。can能；can't不能；should应该；shouldn't不应该。根据句意可知本题选A。
9.(2019北京，4)-Lily, ____you finish the letter in ten minutes?
-Yes, I can.
A. must B. should C. need D. can
【答案】D
【解析】句意：—Lily,你能在十分钟之内完成这封信吗？——是的，我可以。此题考查情态动词的用法。根据答语I can可以推断出问句是在询问能力，要用can来问，因此选D。must必须；should应该；need需要
10.(2019山东青岛，3)As middle school students, we _______ follow the public rules wherever we go.
A. would B. should C. might D. could
【答案】B
【解析】句意：作为中学生，无论走到哪里，我们都应该遵守公共规则。本题考查情态动词。作为学生，遵守公共规则是我们应该做的，故选B。would将会；should应该；might可能；could能。
11.(2018四川成都，34)—Wow...another gift! What's in the box?
-I'm not sure . It _______ be a pair of sports shoes .
A. must B. may C. will
【答案】B
【解析】句意：—哇……又一件礼物！盒子里面是什么？——我不确定。它可能是一双运动鞋吧。本题考查情态动词的用法。must表示有根据、有把握的推测，意为“肯定，一定”；may表示不太肯定的推测，意为“可能，也许”；will表示推测时含有肯定的意思。根据题干中的not sure可知说话人不太肯定，故本题选B
12.(2018湖北武汉，35)-Must you go?
-Yes , I'm afraid I really _______ ,
A. may B. should C. must D. can
【答案】C
【解析】句意：——你必须走吗？——是的，恐怕我真的必须走了。本题考查情态动词的用法。must的肯定回答还应该用must,故本题选择C。知识拓展MustI…？的答语：肯定回答：Yes,you must.否定回答：No,you needn't/don't have to.
13.(2018内蒙古包头，26)-Excuse me, where is the nearest bank ?
-Go straight ahead ; you ______ miss it .
A. mustn't B. can't C. needn't D. shouldn't
【答案】B
【解析】句意：——打扰一下，(请问）最近的银行在哪里？——直向前走，你不会看不见的。can't不会，符合句意。mustn't禁止；needn't 不必；shouldn't不应该
14.(2018上海，34)——Must I do the project on my own?
- No , you ______ . You can work with your classmates .
A. needn't B . can't C. shouldn't D. mustn't
【答案】A
【解析】句意：——我必须独立完成这项专题研究吗？——不，你不必。你可以和同学们一起做。本题考查情态动词。needn't不必；can't不能；shouldn't不应该；mustn't一定不能。用情态动词must提问，否定回答时用needn't易错警示由must引导的一般疑问句，否定回答易错用mustn't。
15.(2018云南，29)——Will you go camping with us, Bob?
- I'd love to , but I ______ study for the test .
A. may B. must C. can D. could
【答案】B
【解析】句意：——Bob,你愿意跟我们一块儿去野营吗？——我很乐意去，但是我必须为考试而学习。本题考查情态动词。may可能，可以；must必须；can能；could可以。根据语境可知，应该选B项。
16.(2018湖北黄冈，29)-Must I finish reading the book today, Mr. Brown?
No, you _______ . You can finish it in two days .
A. needn't B. mustn't C. can't D. couldn't
【答案】A
【解析】句意：——布朗先生，我必须今天读完这本书吗？——不，你不必。你可以在两天内完成它。本题考查情态动词。以情态动词must开头的一般疑问句，其否定回答应用needn't或者don't have to。由此可知本题选择A
易错警示按照用什么提问，就用什么回答的原则，本题易错选B。注意情态动词的几种特殊情况：
——May I...? -No, you mustn't/can't.
-Must I ... ? - No , you needn't / don't have to .
——Could I...? -Yes, you can.
17.(2017北京，25)——— ______ I hand in the report today?
-No, you needn't.
A. Can B. Must C. Shall D. Could
【答案】B
【解析】句意：——我必须今天交报告吗？——不，你不必。本题考查情态动词。根据答语“No,you needn't.”可知用must提问，故选B。
18.(2017上海，41)———— _________I park my car here for a while?
-No, you mustn't. Do you see the sign "NO PARKING"?
A. Would B. May C. Must D. Should
【答案】B
【解析】句意：——我可以把我的车停这里一会儿吗？——不，你不允许停这里。你看到那个“禁止停车”的标志了吗？本题考查情态动词的用法。本题应用may表请求，故选择B。
知识拓展 may 作情态动词可以表示“请求允许”，常译为“可以”；还可以表示“推测”，常译为“可能”。
19.(2017重庆，26)——May I take the dog with me, sir?
_______ . Pets are not allowed to enter the hall .
A. Yes, you may B. No, you mustn't C. Yes, you can D. No, you needn't
【答案】B
【解析】句意：——先生，我可以带着狗吗？——不，不可以。宠物不允许进入礼堂。本题考查情态动词。may可以；mustn't禁止；ca能；needn't不必。根据句意可知，宠物应是被禁止进入礼堂的，故选B项。
20.(2017河南，28)——I don't care what people think.
----Well , you _______ .You’re not alone in this world .
A. can B. may C. should D. will
【答案】C
【解析】句意：——我不在乎人们怎么想。——唤，你应该在乎的这个世界上不只有你自己。本题考查情态动词的用法。can能会；may可能；should应该；will愿意。根据句意可知应该选择C项。
21.(2017湖北武汉，35)—Have you got the results of the exam?
-No. All we _________ do now is to wait.
A. must B. can C. may D. could
【答案】B
【解析】句意：——你得到考试的结果了吗？——没有。现在我们所有能做的就是等待。本题考查情态动词的用法。must必须；ca能，会；may可能，可以；could能（can的过去式）。根据句意可知B项符合题意，故选B项。拓展延伸情态动词can可以表示能力“能，会”；否定形式
can't 既可以表示“不能，不会”还可以表示否定推测“不可能”
22.(2017天津，37)When you are travelling, bring a map because it _________ help you.
A. can't B. mustn't C. used to D. may
【答案】D
【解析】句意：当你旅行的时候带一张地图，因为它可能会帮到你本题考查情态动词。A项意为“不能；不可能”，B项意为“禁止”，C项意为“过去常常”，D项意为“可能”。根据句意应选D项。
23.(2017黑龙江哈尔滨，14)-Must I prepare for the trip today?
——No, you ______prepare for it today . You can do it tomorrow.
A. need B. don't need C. needn't
【答案】C
【解析】句意：——我今天必须为旅行做准备吗？——不，你不必今天做准备。你可以明天做准备。本题考查情态动词的用法。由句意可知A选项不正确。B选项中need为实义动词，其后应加to。needn't意为“不必”，后加动词原形，故本题选择C。
24.(2017四川成都，36)This pair of glasses _________be Tony's. He's the only one who wears glasses.
A. must .B. might C. can't
【答案】A
【解析】句意：这副眼镜肯定是托尼的，他是唯一一个戴眼镜的人。本题主要考查情态动词表推测的用法。情态动词表推测时，must意为“肯定，一定”；might意为“可能”；can't意为“一定不”。由“He's the only one who wears glasses."可知说话人对于这副眼镜属于托尼这件事十分确信，故本题选择A。
25.(2016山西，20)-Many people play with mobile phones all day instead of reading books.
——That's too bad . Everyone _________ be a book lover .Reading is more enjoyable.
A. may B. should C. would
【答案】B
【解析】句意：——许多人整天玩手机而不读书。——那太糟糕了每个人都应该爱读书。读书更令人愉快。本题考查情态动词may也许；should应该；would将会。根据句意可知答案为B项。
26.(2016天津，37)——Mum,____________ I play football this afternoon?
-Sure, but you _______ finish your homework first.
A. may; could B. can; must C. can; mustn't D. may; can't
【答案】B
【解析】句意：——妈妈，今天下午我可以踢足球吗？——当然可以，但是你必须首先完成你的家庭作业。本题考查情态动词的用法。can可以，表示请求；must必须。故选B项。
27.(2016黑龙江哈尔滨，7)—Hi, Jack! Could you come to our English party ?
-Sorry, I_______.I have to look after my little sister at home.
A. must B. could C. can't
【答案】C
【解析】句意：——你好，杰克！你能来我们的英语聚会吗？——双不起，我不能。我得在家照看我的妹妹。本题考查情态动词的用法。must必须；could能；can't不能。根据语境可知答案为C项
28.(2016重庆，28)——Must we finish the work today?
A. Yes, we can B. No, we can't C. Yes, we must D. No, we needn't
【答案】C
【解析】句意：——今天我们必须完成工作吗？——是的，我们必须完成。明天我们还有别的事要做。由“明天有别的事要做”可知此处应作肯定回答。以must开头的问句其肯定回答用：主语must。故选C。
29.(2016宁夏，24)-Can I go swimming, Mom?
——Certainly . But you _________ be back by four .
A. can B. may C. might D. must
【答案】D
【解析】句意：——我能去游泳吗，妈妈？——当然可以。但是你必须在四点前回来。本题考查情态动词。can可以，能够；may或许，可以might或许；must必须。根据句意选D
30.(2016福建福州，25)—Look at the young lady in red. Is it Mrs. Li?
——No. It be her. She is wearing a white dress today.
mustn't B. needn't C. can't
【答案】C
【解析】句意：——看那个穿红色衣服的年轻女士。她是李老师吗？——不，不可能是她。她今天穿着白色的连衣裙。本题考查情态动词。mustn't不准；needn't不必；can't不可能。根据句意应选C。