文档介绍：Grammar & usage
to-infinitive
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Figure out the meanings of the proverbs and the usage of the underlined part.
To know everything is to know nothing.
It is easier to get money than to keep it.
Eat to live, but not live to eat.
什么都知道即如什么都不知道。
挣钱容易，攒钱难。
吃饭是为了生活，但活着不是为了吃饭。
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I. The to-infinitive can be
1. subject of a sentence表示去做或为了统一主语表语形式
To see is to 。
了解英语是一回事，会英语是另一回事。__________ something about English is one thing; __________ English is quite another.
先制定个计划是个好主意。________ a plan first is a good idea.
To know
to know
To make
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Tip:
动词不定式和不定式短语做主语时，常用it做形式主语，其句型结构为：It is +形容词或名词（或词组）+不定式短语…。
这时的形容词常为easy, difficult, hard, good, useful, wrong, right, necessary, impossible, important 等。名词或词组常为a fact, a great day, a great thing, a pity 等。（注意形容词名词是特殊词语时有可能要用ing形式）
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学好英语很难。
________________ is difficult.
= It is difficult ______________.
再见到你真高兴。
It’s a great pleasure to see you again.
To study English well
to study English well
Practice
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如要说明动词不定式的动作的执行者，可在不定式前加一个介词for引导的短语，其句型结构为：It is +形容词+for sb +不定式短语。如：　
富人帮助穷人是对的．
It is right for rich people to help poor people.
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但如果表语是kind, nice, clever, wise, foolish, careless 等描述动作执行者的性格品质的形容词时,则应在不定式前加一个of引导的短语,而不用for, 句型结构为: It is +形容词+ of sb. + 不定式短语。如：
帮助我拿包，你真好．
It’s kind of you to help me with my bag.
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2. object
We hope to know about the truth.
Those Indians ___________ hot food. (想吃)
They ______________ a map. (需要看)
like to eat
need to look at
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Tip
英语中能以不定式作宾语的动词很多，常
见的有afford, decide, expect, hope, learn,choose,help,hope,ask,refuse, promise,wish,pretend,arrange,plan,attempt, dare, manage,agree,prepare,fail,determine,
offer, desire,elect,long,afford,happen,seem.
　find/think/make等动词＋it+形容/名
+ to do sth. it
用做形式宾语．
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I find it easy to learn English well.
我认为和他相处很难．
老师认为参加这个讲座很有必要．
工作人员使小偷从超市偷走东西成为不可能的事。
I feel it hard to get along with him.
The teacher think it necessary to attend