人教版（2019）选择性必修 第三册Unit 2 Healthy Lifestyle Discover Useful Structures课件(共25张PPT)

(共25张PPT)
选择性必修三 Unit 2 to do used as Subjec
Abby张小小
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1. Students can understand the meaning and function of to do used as subject;
2. Students can master the sentence structure of it as the formal subject, and to do is the true subject;
3. Students can tell the difference between to do used as subject and doing used as subject;
3. Students can apply what they have learned into practice;
Teaching objectives
1. _______(prevent) harmful habits like these from dominating a teenager's life is essential.
2. ________(change) bad habits is never easy, even with many attempts.
3. After all, it is not easy _______(break) bad habits.
4. However, during this period, it can be easy for some of them _______(form) bad habits.
Read the following sentences
1. To prevent harmful habits like these from dominating a teenager's life is essential.
2. To change bad habits is never easy, even with many attempts.
3. After all, it is not easy to break bad habits.
4. However, during this period, it can be easy for some of them to form bad habits.
to do作主语与it作形式主语之间的转换
It will take the nutrition specialist an hour to make a balanced diet menu for you.
It is useful to turn to the fitness consultant for advice.
It is illegal and dangerous to take drugs.
It is often harmful to skip breakfast.
不定式作主语，有时根据表达的需要，可以在添加疑问代词或副词，
疑问代词：who，whom，what，which
疑问副词：when，where，how
whether
E.g.
How to break the bad habit is the question.
Where to go hasn't been discussed.
It has not been decided whether to fly to Paris.
”疑问词+to do”作主语
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总结
思考
位置
含义
本质
名词词性
不定式短语在句中做主语。
doing
to do
(something you have already done)
Doing... is my favorite activity
Doing ... often helps me ...
(something you want to do )
To do... is essential for us.
To do ... can help me...
eat fruits and vegetables
drink 8 glasses of water a day
wash hands before meals
have enough sleep
walk after meals
take regular exercise
一【含义】
一般表示具体的或某一次的或将来的动作。
二【位置】
1. To prevent harmful habits like these from dominating a teenager's life is essential.
2. To change bad habits is never easy, even with many attempts.
3. After all, it is not easy to break bad habits.
4. However, during this period, it can be easy for some of them to form bad habits.
句首
it作形式主语, 不定式放句尾
考点一：不定式作主语时的主谓一致原则
单个不定式作主语，谓语动词用_______
两个或两个以上的不定式作主语，若语意一致或作为一个整体，谓语动词用_________
两个或两个以上的不定式作主语，若语意不一致，谓语动词用________
单数
单数
复数
To improve English _____ the most urgent thing for me now.
To love and to be loved _____________is sweet to us.
To build up our physical and mental health and stimulate our interest in learning _______(be) two essential tasks.
Exercises
考点二：it 作形式主语常见的句型
1. It is+形容词+for/of sb +to do sth
E.g.
It is easy for me to learn how to drive.
It is clever of you to apply for the position.
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总结
一般规律：
若形容词 ”描述人的属性，特征”, 用of;
若形容词“描述事或物的特征”, 用for;
It is stupid _______them to quarrel about this question.
It is easy _______ me to learn how to drive.
It is impolite ______ him to say so.
It is important _______ us to express our opinions.
It is clever ______ him to leave that company.
Exercises
2. It is+名词(a pleasure/a pity/an honour...) (for sb)+ to do sth
E.g.
It is an honour to give a speech in behalf of my school.
It is a pity to miss the chance to see your show.
3. It takes/took/will take sb. some time/money to do
做某事花费,某人多长时间(钱)
E.g.
It took me more than an hour to do my homework yesterday evening.
拓展1：it 作形式主语,doing作真正的主语
1. 浪费时间做某事: It is a waste of time doing sth
2. 做某事是没有用的
It's no use/no good doing sth
It's useless doing sth
It is fun/no fun doing sth
拓展2：to do和doing作主语的区别
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。
区别
to do 通常表示一个将来的、具体的内容; (动作)
doing 而则表示一种经常性的、习惯的或抽象的概念。(事情)
to do
作主语
to do 作主语位于句首
it 作形式主语
疑问词+to do 构成不定式短语
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
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总结
1. It is +adj.+(for sb) to do
It is easy for me to learn how to drive.
2. It is +adj.+(of sb) to do
It is clever of you to apply for the position.
Matters need reciting
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总结
3. It is +n.+ to do sth
( an honour, our duty, a pity, a shame)
It is our duty to take care of you.
4. It takes/took sb some time to do sth.
It takes me half an hour to do my housework.
Thank You !