Period 3 Discovering useful structures
The infinitive of the verb as the predicative
Unit 1 Art
观察课文例句，总结to do sth. 的用法。
• 1. Perhaps the best way to understand Western art is to look at the
development of Western painting over the centuries.
• 2.During the Middle Ages, the purpose of Western art was to teach
people about Christianity.
• 3. In this work, Monet's aim was to convey the light and movement
in the scene.
• 动词不定式在句子中作表语。
动词不定式(短语)作表语相当于名词作表语。它和主语处
在同等地位，所指的或是和主语一样的东西,或是主语产
生的结果。常常可以将主、表交换位置,句子的意义不变。
During the Middle Ages, the purpose of Western art was to
teach people about Christianity.
During the Middle Ages, to teach people about Christianity
was the purpose of Western art.
动词不定式(短语)作表语的用法
1.主语是以aim, suggestion, duty, hope, idea, intention, plan, purpose, the way
to do sth.等为中心的名词词组时,或者以what引导的名词性分句表示,一般用
动词不定式作表语说明主语的内容。
My idea is to climb the mountain from the north.我的想法是从北面爬这
座山。
Our plan is to make better use of these materials.我们的计划是更好地利
用这些材料。
What I would suggest is to ask your father for his opinion.我的建议是
征求你父亲的意见。
The best way to encourage your kids to enjoy meals is to involve
them in the planing and preparing.鼓励孩子享受美食的最好方法是让他们参与
计划和准备(美食)。
2.表示目的
The next step is to make sure that you know exactly what is
required.下一步你要真正弄清楚需要的是什么。
3.表示事态发展的结果、预期的结果及预言
You must speak out，if we are to remain friends. 如果我们还想继续做朋友
的话，你就必须把话都说出来。
We believe man is to live a better life in the future. 我们相信人类在将来会
生活得更好。
4.用于被动语态,相当于can/could, should, ought to, must,具有情态意义。
The regulations are to be observed.规章制度必须遵守。(must)
You are to be rewarded.你应受奖励。(should)
5.表示"同意、安排、命令、决定、劝告、愿望、意愿、禁止"等。
They are to marry next week.他们将在下周结婚。(安排)
You must be patient and persistent if you are to succeed.要想成
功,就必须有耐心,有毅力。(愿望)
You are to have a face-to-face talk with them. 你应该和他们当面谈一
谈。（劝告）
Children are not to smoke. 儿童不准吸烟。（禁止）
6.动词不定式(短语)作表语时,可用主动形式表示被动意义。
Who is to blame for the fire?谁该对此次火灾负责?
The house is to let.该房屋出租。
动词不定式(短语)作表语省略to的情况
动词不定式(短语)作表语时，一般情况下不定式符号to不能省略,但在以下几种情况
下可省略不定式符号to:
1. all作主句主语,其后的定语从句中含有实义动词do的某种形式时。
All we need to do is live each day with hope.我们需要做的就是带着希望过好
每一天。
2.what引导的从句作主语,从句中含有实义动词do的某种形式时。
What I want to do is take a holiday right away.我想马上就去度假。
3.(主句)主语被only,first,one,least或形容词最高级修饰,且其后作定语的从句或短语中含
有实义动词do的某种形式时。
In the evening the only thing he did was read the newspaper.晚上他
唯一做的就是看报纸。
动词不定式(短语)作表语和v-ing (短语)作表语的区别
1.动词不定式(短语)和v-ing(短语)作表语时,要注意与句子的主语在形式上保持一致,即若
句子的主语为v-ing(短语)， 则表语也应使用ving(短语)；若主语为动词不定式(短语),则
表语也应使用动词不定式(短语)。
To see is to believe. = Seeing is believing.眼见为实。
2.动词不定式(短语)和v-ing(短语)作表语时可换用,但以下情况除外:
(1)当动词所表达的是某一特定的行为,尤其是将来的行为或有待于实现的行为时,通常用
动词不定式(短语)作表语。
Her best wish is to put her new ideas into practice.她最大的愿望是将自己
的新想法付诸实践。
(2)若动词所表达的并不强调动作,而是表示主语的内容，则通常用v-ing(短语)作表语。
My favorite sport is swimming.我最喜欢的运动是游泳。
What I hate most is being laughed at.我最痛恨的就是被嘲笑。
Complete the sentences:
1.当我13岁的时候,我唯一的目标是成为我们足球队的明星。
When I was 13 my only purpose was _____________(become) the star on our
football team.
2.这些书不应该被卖掉,最好把它们捐给学校。
These books_________________(sell);it's better to donate them to a school.
3.据说他们下星期要去参加一个重要的学术会议。
It's said that they _____________(attend) an important academic conference next
week.
4.别担心,你需要做的就是好好睡上一觉。
Don't worry. What you need to do _____________(have) a good sleep.
5.每天早晨我所做的第一件事就是进行锻炼。
The first thing I do every morning______________(take) exercise.
to become
are not to be sold
are to attend
is (to) have
is (to) take
6.他想做的最有意义的事情就是帮助穷人。
The most meaningful thing he wants to do_______________ (help) the
poor.
7.今年,他的计划是要对教学方法进行一些变革。
This year, his plan____________(make) some changes in the teaching
method.
8.我建议马上开始工作。
What I suggest ____________(start) work at once.
9.她的爱好之一是集邮。
One of her hobbies ____________(collect )stamps.
10.我认为是你弟弟对这次事故负有责任。
I think it is your brother who ___________ (blame) for the accident.
is (to) help
is to make
is to start
is collecting
is to blame
Homework
Finish the exercise in Workbook.
anksThanks!
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