资源简介

Unit 1 Food matters
Grammar and usage (II)
To-infinitives as subjects and predicatives
内容分析：
本板块围绕单元话题,引导学生在有关“外出就餐和在家做饭”的语篇中观察、探究动词不定式做主语和表语的用法，并自主归纳其核心规则；再让学生通过句子、语篇两个层面练习巩固所学、内化新知。
教学目标：
By the end of this section, students will be able to:
identify the use of to-infinitives as subjects and predicatives;
work out the rules of to-infinitives used as subjects and predicatives;
use the right forms of to-infinitives to finish tasks of rewriting sentences and completing a magazine article;
apply to-infinitives in new situations.
教学重难点：
To summarize the general rules;
To apply the rules correctly and properly.
教学过程：
Step 1 Revision
动词不定式作主语
动词不定式具有名词特征，可充当主语。（做主语时谓语动词用单数形式）
To see is to believe.
眼见为实。
To say is one thing and to do is another.
说是一回事，做又是另一回事。
注：单个不定式作主语时，谓语动词用单数形式；两个及以上不定式作主语时，谓语动词用复数形式；但作为一个整体时，谓语动词用单数形式。
到哪里去度假以及何时去度假还没有决定。
Where to go on a holiday and when to go for the holiday ______ (decide).
到哪里去，何时去度假还没有决定。
Where and when to go on a holiday________ (decide).
答案：
have not been decided
has not been decided
动词不定式句子的主语时可以用形式主语it代替，将不定式置于句末，平衡句子结构。
It is a shame to litter.
乱扔垃圾可耻
It is a privilege to meet you.
认识你很荣幸
it 作为形式主语时，常见句型。
It + be +adj. + (for sb) to do sth (adj 修饰物)
It + be +adj. + (of sb) to do sth (adj 修饰人)
It + be + n. + to do sth
It takes/ took/ will take sb some time/money to do sth
动词不定式句子的主语时, 若其后面需要用动词作表语时，则作表语的动词也最好使用不定式形式，保持形式一致 (to do is to do)
To save me is to save yourself.
救我也是救你自己。
动词不定式句子的主语时, 会有时态、语态的变化。
It is a great honor for me to be invited here today.
今天我很荣幸被邀请到这里。
Her birthday party is to be held next Friday.
她的生日将于下周五举行。
动词不定式作表语
动词不定式做表语直接用在系动词之后，起解释说明的作用，其主语通常是 aim, ambition, dream, duty, goal, idea, intention, plan, purpose, task, way, wish等表示意向、打算、计划的词。
Her wish is to be a teacher.
她的愿望是当一名教师。
The duty of soldiers is to defend their country.
军人的职责是保卫祖国。
动词不定式做表语用在seem, appear, remain, prove, turn out等之后：
Several problems remain to be settled.
有几个问题有待解决。
用于表达想法、约定、义务、命令、可能性、命运等。如：
We are to meet at the station at there. ( 表约定）
How are we to convince him （表可能性）
You are to come when I call. （表命令）
“疑问词+不定式”也可以用作表语
The question is how to carry out the plan.
问题是如何实施这项计划。
5. 当All 或what引导的主语从句中有实义动词 do （以及do的其他形式时， 作表语的不定式通常要省略to, 即“前有do, 后无to”
All you should do now is devote yourself to studying hard.
你现在应该做的事就是投入到刻苦的学习当中。
注意：动词不定式作表语时，在结构上是主动的，但在意义上却是被动的。
She is to blame.
她应该受到责备。
The house is to rent.
此房出租。
Step 2 Homework checking
1. to look 2. to be heard 3. to decide 4. shutting 5. to be
6. spent 7. to complete 8. lowered 9. To free 10. to update
Step 3 Additional Exercise
一、单选
1-5 AACCC 6-10 DBBAA 11-15BCBAC
二、用括号中所给单词的正确形式补全句子
1. to be punished 2. give; do 3. to break 4. to collect 5. to cry
6. to be awarded 7. to have been sent 8. to arrive 9. to use 10. to reduce 11. To be accepted 12. to be caused 13. to breathe 14. to be finished
15. to operate
Step 4 Homework
Revision
【设计意图：强化知识运用。】
教学反思

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