Unit 2 Healthy Lifestyle Discover Useful Structures不定式作主语 课件-2025-2026学年高中英语人教版选择性必修第三册

选择性必修三 Unit 2 Healthy Lifestyle Discover Useful Structures 不定式作主语 master the usage of the infinitive as subject. 01 use the relevant grammar flexibly and authentically in real situation. 02 understand the difference between the infinitive as subject and V-ing form as the subject. 03 Learning Objectives 不定式 to do 作表语 结构 S+be to do 形式 用法 （1）表示主语的内容。 （2）表示事态发展预期的结果、不幸的命运等。 （3）用于第一人称疑问句，表示征求意见。 （4）表示“同意、安排、命令、决定、劝告、意愿、禁止”等。 常见情况 （1）主语常是表示方式、目的、计划、梦想、责任等的词，如way, intention, purpose, aim, attempt, plan, duty, dream等。 （2）what引导的名词性从句。 （3）当主语有all, 或者主语被序数词、或the only, the last或形容词最高级修饰时，其后可接“系动词+不定式”作表语。 省略to 前有do, 后省to Review Unit 1 不定式 to do 作表语 1.不定式(短语)置于句首作主语 2.it作形式主语 3.动词不定式作主语时的语态 4.to do和doing作主语的区别 单个 2个或以上 谓语动词：单数 语义一致：单数 语义不一：复数 It takes sb. time/money/energy to do sth. It is + adj. + （for/of sb.） to do sth. It is + n. + (for sb.) to do sth. 经常性/习惯性/抽象性 具体的、一次性的或将来的 to do doing Preview Lead-in Look at the following sentences and pay attention to the italicised infinitives. Find more infinitives in the reading passage. In pairs, discuss their meanings and functions. 1 To change bad habits is never easy. 2 It took the surgeon (n.外科医生) three hours to finish my mother’s lung surgery (n. 外科手术). 3 To join the People’s Liberation (n. 解放) Army , it is required for men to shave off (剃掉,刮掉)their beards. 4 It was not polite to disturb(v. 打扰)your neighbours with loud music last night. 主语 主语 主语 主语 状语 Presentation 1 Explore grammar-不定式(短语)置于句首作主语 To see is to believe. To get up early is necessary. To prevent harmful habits like these from dominating a teenager’s life is essential. (para 1) Summary 1 1.不定式作主语通常位于______，表示具体的某次动作，谓语动词用______。 注意：当句子主语和表语都是非谓语时，通常要保持一致。 句首 单数 Explore grammar-不定式(短语)置于句首作主语 1. To learn English well and to master a skill _______ (be) very important for your future. 2. To jog every morning and to do some stretching exercises in the evening _______ (be) good ways to keep fit. 两个或两个以上的不定式作主语时： 若语义_________或不定式_____________，谓语动词用_____； 若语义不一致，则用______。 3.To love and to be loved _____ sweet to us. are are is Summary 2 基本一致 作为一个整体 单数 复数 Presentation 1 Explore grammar-不定式(短语)置于句首作主语 Summary 3 ________ (怎样) to handle the rubbish is the question. ________ (去哪)to go for dinner has not been decided. How Where 1.________ 和动词不定式构成不定式短语作主语 2.可用于该结构的疑问词 疑问代词: 疑问副词: 疑问词 who,whom,what,which when,where,how ①When and where________ (vote) hasn’t been decided. ②______________（何时装修） the house hasn’t been decided When to decorate to vote Presentation 1 Explore grammar--it作形式主语 It is important to keep a balanced diet and do exercise regularly.​  To keep a balanced diet and do exercise regularly is important. 主语 动词不定式作主语时，若不定式太长，为避免头重脚轻，常用it作形式主语，将真正的主语置于后面。 Presentation 2 Summary 1 It is＋adj.＋(for/of sb) to do sth.(对某人来说)做某事是…… ①It is ＋ adj. ＋for sb. to do sth. 表示的是_____________________________ 用于此句型的形容词有： ________________________________________________________________________________________________________________________ easy, hard, difficult, possible, important, essential, impossible, necessary, good, bad, exciting, interesting, surprising, inconvenient等。 It is important for us to drink enough water.​ It is difficult for us to finish writing the composition in a quarter of an hour. 事物或行为的特点或性质 sb. 是to do sth. 的逻辑主语 Explore grammar--it作形式主语 Presentation 2 Summary 1 It is＋adj.＋(for/of sb) to do sth.(对某人来说)做某事是…… ②It is ＋ adj. ＋of sb. to do sth. 表示的是_______________________________________ 用于此句型的形容词有： ________________________________________________________________________________________________________________________ pity, shame, pleasure, one’s duty, one’s job, fun, joy, good manners, bad manners, careless, clever, kind, foolish, honest, impolite, lazy, wise等 It is impolite of you to disturb others. It was foolish of him to make such a mistake. 不定式的逻辑主语的性质、身份、特点 sb. 是to do sth. 的逻辑主语 Explore grammar--it作形式主语 Presentation 2 Summary 2 It is＋n.＋（for sb.）to do sth. 做某事是…… 常见的名词有： ________________________________________________________________________________________________________________________ pity, shame, pleasure, one’s duty, one’s job, fun, joy, good manners, bad manners等 It is a hard task to change long habits in a short time. It is a doctor’s duty to heal the wounded and rescue the dying. Explore grammar--it作形式主语 Presentation 2 Summary 3 It takes / took / will take sb. time / money / energy to do sth. 花某人时间/金钱/精力做某事 1.It takes me 30 minutes to do yoga every evening. 2.It took him lots of energy to climb the mountain. 3.It will take them some money to buy sports equipment. Explore grammar--it作形式主语 Presentation 2 小结 it作形式主语代替真正主语不定式常见于以下情况中： It is + adj. + for/of sb. to do sth. It is + n. + (for sb.) to do sth. It takes/took/will take sb. time / money / energy to do sth. Explore grammar--it作形式主语 Presentation 2 Presentation 3 Explore grammar--动词不定式作主语时的语态 Summary 动词不定式作主语时,如果不定式和逻辑主语之间是主动关系应使用to do, 如果是被动关系应使用 _________。  ①It was an honour for him to be chosen as head of the medical team. ②To finish the task will take a long time. to be done Presentation 3 Explore grammar--动词不定式作主语时的语态 Summary 动词不定式作主语时,如果不定式和逻辑主语之间是主动关系应使用to do, 如果是被动关系应使用 _________。  ①It was an honour for him to be chosen as head of the medical team. ②To finish the task will take a long time. to be done 类别 主动形式 被动形式 时间 一般式 完成式 进行式 to be done to have done to be doing to have been done 发生在谓语动词之后 发生在谓语动词之前 正在进行 to do Presentation 4 Explore grammar--不定式作主语和动词-ing形式作主语的区别 Summary 动名词作主语表示______________________的行为;不定式作主语表示 _________________________ 动作。 ①To have an 8-hour sleep is my plan today. ②Having an 8-hour sleep is my daily routine. 经常性/习惯性/抽象性 具体的、一次性的或将来的 1. ______ (do) morning exercises regularly is good for your health. 2. It feels really good ______ (do) morning exercises today. Doing to do 不定式 to do 作表语 1.不定式(短语)置于句首作主语 2.it作形式主语 3.动词不定式作主语时的语态 4.to do和doing作主语的区别 单个 2个或以上 谓语动词：单数 语义一致：单数 语义不一：复数 It takes sb. time/money/energy to do sth. It is + adj. + （for/of sb.） to do sth. It is + n. + (for sb.) to do sth. 经常性/习惯性/抽象性 具体的、一次性的或将来的 to do doing Summary Notice 不定式短语作独立成分 to begin/start with 首先 to sum up 总而言之 to conclude 总而言之 to tell the truth 说实话 to be frank 坦白地说 to be honest 说老实话 to be brief 简言之 一些不定式短语可用作独立成分，通常位于句首，有时位于句中或句末，要用逗号同其他句子成分隔开。 To tell the truth，I don’t like the gifted actress in the movie. 说实话，我不喜欢这部影片中的那个有天赋的女演员。 （1） 　　　　　 　　　（总而言之），most of the committee members supported the idea but a few were against it. （2） 　　　　　（简言之），he was happy with the result. （3）She wrote， 　　　　　（确切地说），ten novels in her lifetime. （4） 　　　　　　　　（首先），he’s too young for that kind of job. （5） 　　　　　 （说老实话），I don’t really want to go to the party tonight. To sum up/To conclude To be brief to be exact To begin/start with To be honest Practice Join the words to make full sentences, and then join the sentences to make a paragraph. You can add your own sentences if necessary to make your paragraph more meaningful. 1. important / avoid / passive cigarette smoking It is important to avoid passive cigarette smoking. 2. will take / nutrition specialist / a balanced diet menu / make / an hour / for you 3. useful / turn to / fitness consultant / for advice It will take an hour for a nutrition specialist to make a balanced diet for you. It is useful to turn to the fitness consultant for advice. 4. illegal / dangerous / take drugs 5. harmful / skip breakfast / often It is dangerous to take illegal drugs. It is harmful to skip breakfast (too) often. Practice Complete the conversations with the correct forms of the phrases in the box. 1.A: Hello, doctor. I want to lose weight, but I just can’t seem to do it. What can you do to help me? B: Well, first, it’s necessary to ________________ what you eat. Cut out all fatty food and sugary drinks, and eat more fruit and vegetables. 2.A: I really need to ____________ a way to exercise more. I could use a fitness app, but my phone’s full. B: So delete a few files. I’m sure the app doesn’t take up much space. be in control of begin with, be in control of, make a choice, decide on, make up one’s mind decide on Practice Complete the conversations with the correct forms of the phrases in the box. begin with, be in control of, make a choice, decide on, make up one’s mind 3. A: Before exercising, always do a few warm-ups to ___________. B: I know. But then I always feel too tired to continue! begin with 4. A: Should I go for the pizza or the fried chicken? I hate _________________ like these. You know what — I’m going to eat both! B: Wow! Don’t eat too much junk food — you’ll get fat, I’ve actually __________________ to go on a diet, so I’ll just stick to the fruit salad. making choices made up my mind Translation 1.对中学生来说，每天吃一顿营养早餐很重要。 It is + adj. + for sb. + to do sth.​ 2.你坚持每天跑步来增强体质真是太有毅力了。 It is + adj. + of sb. + to do sth.​ 3.睡前长时间使用电子产品是个不好的习惯。 ​It is + a/an+n. + to do sth.​ 4.每周花两小时阅读文学作品能帮助我们放松心情。 ​It takes sb. + time + to do sth.​ 5.培养一个爱好，比如跳舞是缓解压力的好方法。 It is + a/an+n. + to do sth.​ ​ 应用实践：翻译句子 1.对中学生来说，每天吃一顿营养早餐很重要。 2.你坚持每天跑步来增强体质真是太有毅力了。 3.睡前长时间使用电子产品是个不好的习惯。 4.每周花两小时阅读文学经典能帮助我们放松心情。 5.培养一个爱好，比如跳舞是缓解压力的好方法。​ It is important for middle school students to have a nutritious breakfast every day. It is determined of you to keep running every day to build up your body. It is a bad habit to use electronic products for a long time before going to bed. It takes us two hours to read classics every week to help us relax. It is a good way to develop a hobby like dancing to relieve stress. $