2021年度英语中it用法讲义.ppt

it用作主语
it指代事物、动物、婴儿或未知的人
What is this?--It is a book.
Someone is at the door.--Who is it?
Her new baby is only weighs 2 kilos.
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英语中it用法
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指代天气、时间、距离、季节、事物的状态和自然环境等
It is getting colder and colder.
It is two years since I last saw you.
It was very quiet in the cafe.
How is it with ?
It is only twenty minutes' drive to our college.
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英语中it用法
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it 作形式主语，代替不定式、动名词或从句，使原来的这些主语可以放在句子后面，避免句子头重脚轻。

It cost me $25 to buy the dictionary.
Is it necessary to complete the design before National Day?
It's a good idea to have a little note book handby.
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英语中it用法
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注意：有时不定式前面有一个for引起的短语，表示不定式逻辑上的主语，用it作形式主语时，构成下面句型
It is+adj.+for sb.+to do
此句型中的形容词为静态形容词，即描写人或物的静态特征的形容词，用来表示客观情况。这样形容词有：
easy,difficult, important,hard,necessary,essencial,
impossible,dangerous,common,unusual,big,
small,tall,long,short,wide,old,young,beautiful等
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英语中it用法
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It is very difficut for me to learn Spanish.
It is getting harder every day for a poor man to get a living.
注意：有时不定式前面有一个of引起的短语，表示不定式逻辑上的主语，用it作形式主语时，构成下面句型：It is+adj.+of sb.+to do
此句型中的形容词为动态形容词，即指那些有动作含义的词，或为描写人或物的特征或品质的形容词，这样的形容词有：
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英语中it用法
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bold,brave,busy,careful,careless,clever,considerate,cruel,foolish,friendly,generous,good,honest,kind,lazy,nice,noisy,polite,rude,reasonable,selfish,shy,silly,stupid,thoughtful,wicked等
It was generous of you to contribute so much.
It was careless of her to lose her key of the safe.
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英语中it用法
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，而作主语的动名词常放在表语后，在此句型中的表语有下列名词和形容词：
no good,no use,a waste of time,fun,hard work,pity,a wonder,dangerous,difficult,
senseless,useless,foolish,nice,hard,
interesting,worth,worthwhile,terrible,tiring,
funny
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英语中it用法
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It’s no use studying for an exam at the last minute.
It is difficult finding your way around here.
，有以下四个常见句型
1)It+be+adj.+that从句
这样的adj通常有：
possible/probable/likely 很可能
impossible/unlikely 不可能
obvious 显而易见
certain 很肯定
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英语中it用法
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plain