一、考點聚焦
1、it的基本用法
（1）用作人稱代詞，代替前文提到過的事物。
The train has arrived. It arrived half an hour ago.
（2）用以代替提示代詞this, that。
-What’s this? -It’s a knife.
-Whose watch is that? -It’s mine.
（3）起指示代詞的作用，指一個人或事物。
-Who is knocking at the door? -It’s me.
（4）指環(huán)境情況等。
It was very noisy (quiet) at the very moment.
（5）指時間、季節(jié)等。
-What time is it? -It’s eight o’clock.
It often rains in summer here.
（6）指距離。
It is a long way to the school.
（7）作形式主語。
It is not easy to finish the work in two days.
It is no use crying over spilt milk.
It is as pity that you didn’t read the book.
（8）作形式賓語。
I think it no use arguing with him.
I found it very interesting to study English.
He made it clear that he was not interested in that subject.
（9）用于強調(diào)結(jié)構(gòu)。
It was Xiaoming whom(that)I met in the street last night.
It was in the street that I met Xiaoming last night.
It ws last night that I met Xiaoming in the street.
It was I who met Xiaoming in the street last night.
2、含有“It is …”的句型
（1）It is time (for sb.) to do sth.
It is (high) time that sb. did sth.(虛擬語氣)
（2）It is + 形容詞（+of / for sb.）+ to do sth.
通常用 of的詞有brave、clever、careful、hopeless、kind、good、naughty、nice、silly、stupid、foolish、wise等。
（3）It is + 形容詞 + that + sb. + (should) do sth.（虛擬語氣）
能用于這個句型的形容詞有strange、wonderful、natural、good、proper、right、wrong、well、fortunate、important、necessary、useless、likely、probable、impossible等。有時可省去should而直接用動詞原形。如：
It is important that we should pay close attention to grain.
It is natural that he（should）say so.
（4）It is no use/ good + doing sth.
It is no use trying again = It is of no use to try again.
（5）It is + 被強調(diào)部分 + that/who + …
Was it in the street that you met her?
Who was it that called him“comrade”?
It was not until yesterday that I met my old friend.
It is in a small factory that my brother is going to work.（注意上述各句均為強調(diào)句型的“考點”）
比較：It is a small factory where my brother is going to work.（定語從句）
（6）It is said/reported/announced/ (well) known … that…
（7）It is/was + 時間 + since … 從……已多久了。
It is three years since I met him in Beijing.
It was a long time since I (had) lived in that small mountain village with these farmers.（注意兩句中的時態(tài)）
It is five months since I arrived in New York.我到紐約已經(jīng)五個月了。
It is five months since I was in New York.我離開紐約已經(jīng)五個月了。
（注意：終止性動詞表示從動作發(fā)生時算起；如果是狀態(tài)動詞或持續(xù)性動詞，則從動作或狀態(tài)結(jié)束時算起。）
（8）It is + 時間 + before …
這個句型和上面句型中時間都是時間段，如long、years、months、weeks、five days、three hours、twenty minutes等。不過主句的時態(tài)多用一般將來時或一般過去時。
It will be several years before we meet again.
我們要過好幾年才能再見面。
It was not long before they set out for the front.
不久他們就出發(fā)去了前線。
（9）It is /was/will be the first/second/third … time that …
It is the first time that I have been here.
It was the second time that he had seen the film.
（10）It is up to sb. to do sth … 應由某人做某事。
It is up to you to decide whether we start or not.
二、精典名題導解
選擇填空
1. _________ is a fact that English is being accepted as an international language.(NMET 1995)
A.There B.This C.That D.It
解析：答案為D。本題考查作形式主語的用法。that引導的從句是真正的主語。為避免頭重腳輕而平衡句子結(jié)構(gòu)，將it置于句首作形式主語。
2. I hope there are enough glasse for each guest to have ________.(NMET 1995)
A.it B.those C.them D.one
解析：答案為D。本題考查替代詞it和one的區(qū)別。it用于替代同類的、特定的、同一的事物；one替代同類的、泛指的人或物。根據(jù)題意“我希望有足夠的杯子使每個客人有一個�！笨芍獞胦ne泛指enough glasses中的一個。
3. Was __________ that I saw last night at the concert?
A.it you B.not you C.you D.that yourself
解析：答案為A。本題考查強調(diào)句型的疑問式。只須將句序變?yōu)殛愂鼍浔悴浑y得出答案。
三、常見用法有以下幾類：
1、it可用于代替上文中提到的那一個事物。
2、it可用于代替上文中說到的一件事。
3、it可用于代替不知情的人（尤其是不知身份、性別和姓名的人）。
4、it可用于表示時間、天氣、距離、計算結(jié)果等。
5、it可用于代替不定式、動名詞、從句等，充當形式主語。其常用句型為： It---be---adj./ n. / v-ed---to+V/ V-ing/ Clause
6、it 可用于代替不定式、動名詞、從句，充當形式賓語，把真正賓語（不定式、動名詞、名詞或從句）置于句末。其常用句型為： S---Vt---it---adj./ n.---to+V / V-ing /n./ Clause
7、 it可用于構(gòu)成強調(diào)句，把一個句子中除謂語以外的句子成分（如主語、賓語、表語、狀語等）提到句首加以強調(diào)。其構(gòu)成形式是：It is(was) + 被強調(diào)成分（不能改變被強調(diào)成分的數(shù)和格）+ that/ who+原句剩余部分
8、it常用于一些固定結(jié)構(gòu)中，作無人稱代詞用，充當主語等。
it用法專題練習1：
1---What’s this? ---_______ a map of China
A.This is B.That’s C.It’s D.There’s
2---Where is my pen? ---_____on the desk.
A.This is B.That’s C.It’s D.There’s
3I was disappointed with the film. I had expected_____to be much better.
A.it B.this C.them D.one
4They often help us with our research. ______kind of them.
A.They are B.You are C.It is D.This is
5Tom’s mother kept telling him to work harder, but______didn’t help.
A.he B.she C.this D.it
6John passed the exam successfully and _____was more than we had expected.
A.he B.it C.this D.there
7---Who’s knocking at the door? ---_____ me.
A.It’s B.I’m C.That’s D.This is
8---Who’s the baby in the photo? ---_____ my brother.
A. This is B.That’s C.It’s D.There’s
9_____ Sunday today. Let’s go for an outing.
A.There is B.It’s C.This is D.That’s
10_____ was raining heavily when the film was over.
A.Weather B.Sky C.It D.There
11______a long way from my home to the school.
A.It is B.This is C.There is D.There has been
12---What’s ten added to six? ---______ sixteen.
A.There is B.It is C.This is D.We have
13_____ important to learn English well.
A.This is B.That’s C.It’s D.There’s
14_______ great fun to play basketball after school.
A.It has B.It is C.This is D.Ther