It 句型与常考句式

本节导读

英语里有一批用 it 开头的固定句型，还有一批不能拆开记的固定句式（too…to…、would rather…than… 等）。它们在词汇与语法题里出现频率很高，而且每个都有固定的搭配，背熟就能拿分。

学完这一节，你应该能分清 it 作形式主语和形式宾语的用法，记住 It takes…to do、It is…since… 等时间句型，并掌握常考的固定句式。

it 作形式主语

不定式、动名词或从句作主语时，常常把真正的主语放到句子后面，前面用 it 代替。

句型	例句
It is + 形容词 + for sb. to do	It is important for us to keep fit.
It is + 表示人品质的形容词 + of sb. to do	It is kind of you to help me.
It is + 名词 + that 从句	It is a pity that you missed the chance.
It is said/reported/believed that…	It is said that he is ill.
It seems/happens/occurs to sb. that…	It occurred to me that I had left my keys at home.
It is no use/no good doing…	It is no use crying over spilt milk.

it 作形式宾语

在 think、find、make、consider、feel 等动词后面，如果宾语补足语前面的宾语是不定式或从句，就要用 it 作形式宾语，把真正的宾语放到后面：

英语	中文
I find it hard to learn English well without practice.	我发现不练习很难学好英语。
She made it clear that she did not agree.	她明确表示不同意。
We think it necessary to take exercise every day.	我们认为每天锻炼是必要的。

形式宾语 it 不能省略，所以 I find hard to learn English 是错的。

表示时间的 It 句型

句型	例句
It takes sb. + 时间 + to do	It took us three hours to finish the work.
It is + 时间 + since + 过去时的从句	It is ten years since I last saw him.
It will be + 时间 + before + 一般现在时的从句	It will be a long time before we meet again.
It was not long before + 一般过去时	It was not long before he came back.
It is the first time that + 现在完成时	It is the first time that I have been here.
It is (high) time that + 过去式或 should do	It is high time that we went home.

这些句型里，since 引导的从句用一般过去时；before 引导的从句，主句是将来时就用一般现在时，主句是过去时就用一般过去时。

常考的固定句式

句式	例句
would rather do than do	I would rather stay at home than go out.
prefer A to B	I prefer walking to cycling.
had better (not) do	You had better take an umbrella.
too…to…（太……而不能……）	He is too young to go to school.
…enough to…	He is old enough to go to school.
be about to do… when…	I was about to leave when the telephone rang.