Unit 2 Healthy Lifestyle Discover useful structures 不定式做主语语法课件-2025-2026学年高中英语人教版选择性必修第三册

Discovering Useful Structures 新人教选择性必修三 Unit 2 Healthy Lifestyle Infinitives as Subject 不定式作主语 . ✎ Learning objectives ✎ to identify and summarize “to do” structure as the subject; to apply “to do” structure as the subject properly to real situations. Discover Useful Structures Lead-in However, during this period, it can be easy for some of them ________ bad habits. 【教材回顾】 1. However, during this period, it can be easy for some of them ________(form) bad habits. 2. _________ (prevent)harmful habits like these from dominating a teenager’s life is essential. 3. _________(change) bad habits is never easy, even with many attempts. 4. __________(facilitate) a positive change in our bad habits, we must first examine our bad habit cycles and then try to adapt them. 5. when we come to an escalator (cue), our normal routine is _______(ride) it, but we could change this routine into something more positive by taking the stairs instead. 6. In fact, the most successful way _________(change) is not suddenly, but over a period of time. 7._________(reach) the goal of change, a person must show some discipline and repeatedly take many small steps. 8. After all, it is not easy _______(break) bad habits. to form To facilitate to ride to change to break To change To prevent To reach However, during this period, it can be easy for some of them ________ bad habits. 1. However, during this period, it can be easy for some of them ________(form) bad habits. 2. _________ (prevent)harmful habits like these from dominating a teenager’s life is essential. 3. _________(change) bad habits is never easy, even with many attempts. 4. __________(facilitate) a positive change in our bad habits, we must first examine our bad habit cycles and then try to adapt them. to form To facilitate To prevent To change Pay attention to the red italicized infinitives and discuss the meanings and functions of the italicised infinitives. 主语 主语 主语 目的状语 ✎ 探索发现 ✎ However, during this period, it can be easy for some of them ________ bad habits. 5. when we come to an escalator (cue), our normal routine is _______(ride) it, but we could change this routine into something more positive by taking the stairs instead. 6. In fact, the most successful way _________(change) is not suddenly, but over a period of time. 7._________(reach) the goal of change, a person must show some discipline and repeatedly take many small steps. 8. After all, it is not easy _______(break) bad habits. to ride to change to break To reach 表语 后置定语 目的状语 主语 ✎ 探索发现 ✎ 主语 Infinitives as Subject 不定式作主语 2. _________ (prevent)harmful habits like these from dominating a teenager’s life is essential. 3. _________(change) bad habits is never easy, even with many attempts. 1. However, during this period, it can be easy for some of them ________ bad habits. 8. After all, it is not easy _______(break) bad habits. To prevent To change to form to break 系动词 表语 to do 不定式放在句首作主语 主语 系动词 表语 真正主语 形式主语 系动词 表语 形式主语 系动词 表语 真正主语 用 it 作形式主语，放在句首，把真正的主语 — 动词不定式置于句后。 ✎ 探索发现 ✎ To see _____(be) to believe. To get good _______(require) a lot of hard work. To learn a skill _____(be) very important for everyone in society. To change bad habits _____(be) never easy, even with many attempts. is is is requires ✎ Exercise ✎用所给词的适当形式填空并翻译句子。 ✎ Explore grammar ✎ 动词不定式作主语---主谓一致 总结：①动词不定式作主语时，通常位于句首，表示具体的某次动作，谓语动词常用__________。 单数 ✎ Explore grammar ✎ 动词不定式作主语---主谓一致 1. 做喜欢的事，见想见的友乃人生最快乐的事 To do what you love and to meet the friends you want to see are the happiest things in life. 2. 爱与被爱 是人所能得到的最大幸福。 To love and to be loved is the greatest happiness one can get. 总结：②两个及以上动词不定式作主语，谓语动词用复数形式。 总结：③两个并列的不定式语义基本一致，谓语动词用单数形式。 直接置于句首（较正式/强调），通常用于不定式短语较短，或为了强调动作本身时。 ✎ Explore grammar ✎ 一、动词不定式直接作主语，放在句首 1. 喝桂花茶有益身体 To drink osmanthus tea benefits the body. 2. 沿石桥散步令人放松 To walk along the stone bridge is relaxing. 3. 采摘鲜花是不被允许的 To pick fresh flowers is not allowed. 不定式作主语基本用法： 总结：动词不定式直接置于句首（较正式/强调），通常用于不定式短语较短，或为了强调动作本身时。 核心结构：To + 动词原形 + 谓语（单数） + 其他成分 常置于句末 ✎ Explore grammar ✎ 二、动词不定式作主语，常置于句末 不定式作主语基本用法： 总结：当主语较长，谓语较短时，常用it作形式主语放在句首，而将真正的主语—不定式放到谓语的后面。 标准句型结构：It is + 形容词/名词 + to do sth. 1. 这家人对我很友好，使我在他们家里感到宾至如归 It is friendly of the family to make me feel at home in their house. 2. 代表我的学校发表演讲是我的荣幸。 It is an honour to give a speech on behalf of my school. 3. 外科医生花了三个小时才完成手术。 It took the surgeon three hours to finish the operation. It is your fault not to get there in time ! to do作主语，位于句末。 It takes us an hour (get) there by bus. It’s our duty (help) the poor. It is a great enjoyment (spend) our holiday in the mountains. It + takes/took/will take(sb.)+ 时间(金钱)+ to do sth 句型 1 句型 2 It is + 名词 + to do sth. to get to help to spend 常见的名词有： pity, shame, pleasure, one’s duty, one’s job, fun, joy, good manners, bad manners等 ✎ Explore grammar ✎ 不定式作主语，置于句末的基本用法： ✎ Exercise ✎ It will take half an hour ________(send) her to her destination. It will take a nutrition specialist an hour _________(make) a balanced diet menu for you. As a chef, _______ was my duty to cook. It is a pity _______(miss) the chance to see your show. ______ took me more than an hour to do my homework yesterday evening. to make it to miss 用所给词的适当形式填空并翻译句子。 It to send It is easy for me to finish this work before ten. It is + 形容词 + for sb. + to do sth. 句型 3 It is + 形容词 + of sb. + to do sth. 句型 4 It is very kind of you to give me some help. ✎ Explore grammar ✎ 不定式作主语，置于句首的基本用法： 若adj. “描述人的品格、特点”， 用of，如 kind, nice, wise, silly, polite, impolite, friendly, foolish, clever; 若adj.“描述事或行为的特征”， 用for，如easy, hard, difficult, possible, important, impossible, necessary, good, bad,  exciting, interesting, surprising It + 谓语动词 + to do + 其他. 其它 ✎ Explore grammar ✎ 不定式作主语，置于句首的基本用法： It matters to do sth 做某事很重要 It happens to do sth 碰巧做某事 It seems to do sth 似乎要做某事 1.It matters to follow the emperor's order. 遵从皇上旨意至关重要 2.It happens to meet my old friend in the road. 恰巧在路上遇见了我的老朋友。 3.It seems to rain in the city. 这个城市好像要下雨了。 ✎ Summary ✎ It is necessary ______ young students to learn a foreign language. It was silly ______ you to give up such a good chance! It is important _______ us to express our opinions. It was not polite ______ you to disturb your neighbours with loud music last night. It is necessary for you ________(change) your job. Show time for of of for to change it作形式主语的常见句型 It is + 形容词（+ for sb.）+ to do sth. It is easy for me to learn how to drive. It is + 形容词（+ of sb.）+ to do sth. It is clever of him to leave that company. ③It takes/took sb. + some time + to do sth. It takes me an hour to do homework every day. ④It is + 名词（a pleasure/a pity/an honor...）+ to do sth. It’s our duty to take care of the old. ✎ Summary ✎ It + 谓语动词 + to do + 其他. 动词不定式与疑问词连用构成不定式短语作主语。 Where to travel is unsure. Whether to have a holliday is undecided. 总结：特殊疑问词who, whom, whose, what, which, when, where, how+不定式短语做主语。或者连词whether + 不定式短语做主语 ✎ Explore grammar ✎ 三、“疑问词+动词不定式”作主语 ✎ Exercise ✎ 1.When ________(start) has not been decided yet. 2. How ________(use) the computer is the question. 3.Where ________(go) has not been decided. 【应用实践】根据汉语句意完成英语句子。 ①何时离开还没有决定。______ ____ ______ has not been decided. ②如何开始比到哪里停止还困难。 ____ ____ ______ is more difficult than ______ ____ ______ . 用所给词的适当形式填空并翻译句子。 to start to use to go When to leave How to begin where to stop To look after children is her job today. 她今天的工作是看孩子。 Looking after children is her work. 她的工作是照顾孩子。 [Summary]不定式作主语和动词-ing形式作主语的区别： 动名词作主语表示_______________的行为；不定式作主语表示 _________________________ 动作。 经常性或习惯性 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 ✎ 难点突破 ✎ ✎ Exercise ✎ 1.It took years of work ___________ (reduce) the industrial pollution and clean the water. 2.__________ (walk) is a good form of exercise for both the young and the old. 3.To do this _____ (be) to cut the feet to fit the shoes. 4._____ is difficult for him to admit his mistakes. 5.It was selfish _____ him not to share his dictionary with others. to reduce Walking is It of ✎ Exercise ✎ 一、连词成句(Page17) 1. important / avoid / passive cigarette(香烟) smoking ____________________________________________________________ 2. will take / nutrition specialist(营养专家) / a balanced diet menu / make / an hour / for you ____________________________________________________________ 3. useful / turn to / fitness consultant(健身顾问) / for advice ____________________________________________________________ 4. illegal / dangerous / take / drugs ____________________________________________________________ 5. harmful / skip（跳过） breakfast / often ____________________________________________________________ It will take nutrition specialist an hour to make a balanced diet menu for you. It is useful to turn to fitness consultant for advice. It is illegal and dangerous to take drugs. It is harmful to skip breakfast often. It is important to avoid passive cigarette smoking. 毒品/药物 二、Complete the conversations with the correct forms of the phrases in the box. 1. A: Hello, doctor. I want to lose weight(减肥), 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(停止；切断) all fatty food and sugary(含糖的) drinks, and eat more fruit and vegetables. be in control of begin with, be in control of, make a choice, decide on, make up one’s mind 首先 控制；掌控 做出选择 下定决心 选定 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(占据) much space. 3. A: Before exercising, always do a few warm-ups(热身活动) to ___________. B: I know. But then I always feel too tired to continue! begin with, be in control of, make a choice, decide on, make up one’s mind decide on begin with 二、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 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(节食), so I’ll just stick to(坚持) the fruit salad. making choices made up my mind 二、Complete the conversations with the correct forms of the phrases in the box. 1. It takes us hours __________________ every day. 我们每天要花上数小时做家庭作业。 2. __________________ will take a long time. 要完成这项任务将要花费很长时间。 3. __________________ in one day is impossible. 在一天内完成这项工作是不可能的。 4. _____________________ a foreign language well. 要把一门外语学好不容易。 5. It’s very interesting _________________. 踢足球很有趣。 6. Father criticized me and told me it’s wrong _______________________. 父亲批评了我并且告诉我捉弄别人是错误的。 to play football to play tricks on other people ✎ Exercise ✎ to do our homework　 To finish the task To finish this job It’s not easy to learn Summary to do to do 作主语位于句首，在谓语之前 to do 作主语位于谓语之后，It作形式主语 疑问词+to do 构成不定式短语，作主语 和-ing 作主语的区别 To read without reflecting is like eating without digesting. It takes sb. time/money to do sth. It is + adj. + (for/of sb.) to do sth. It is + n. + (for sb.) to do sth. to do 表示具体的，将来的动作 -ing 表示一般的，已经完成的动作 与疑问词who, whom, whose, what, which, when, where, how等连用 ✎ Summary ✎ 种类 形式 主动 被动 主语 宾语 宾补 表语 定语 状语 不定式 一般式 to do to be done √ √ √ √ √ √ 进行式 to be doing × 完成式 to have done to have been done 动名词 一般式 doing being done √ √ × √ √ × 完成式 having done having been done ✎ 非谓语动词的形式及句法功能 ✎ 分词 现在分词 一般式 doing being done × × √ √ √ √ 完成式 having done having been done 过去分词 一般式 done(vi.) 表完成 done(vt.)表被 动与完成 × × √ √ √ √ ✎ 非谓语动词的形式及句法功能 ✎ Homework Early to bed and early to rise makes a man healthy, wealthy, and wise. 1. Draw a mindmap to review what you have learned about the infinitives. 2. Use infinitives to write 3 sentences about healthy lifestyle. ✎ Homework ✎ Early to bed and early to rise makes a man healthy, wealthy, and wise. To exercise regularly is essential for good health. It is important for mental well-being to engage in social activities and maintain relationships. Discovering Useful Structures 新人教选择性必修三 Unit 2 Thank You ! $