李國勤

一、代詞it的用法：

A. 用于指代this, that或前面提到或?qū)υ掚p方心目中的人或事物。如：

1. ——Whats this in English?

——Its a pen.

2. The general manager will inspect our workroom this afternoon. Have you heard about it?

B. 在性別、身份不詳時(shí)指人或指嬰兒。如：

——Someone is knocking at the door. Who can it be?

——Its me.

C. 表示時(shí)間、距離、溫度、環(huán)境、天氣等自然現(xiàn)象。如：

Its early midnight now. Wed better go to bed. （表時(shí)間）

Its about a quarters ride from here to the train station. （表距離）

Its quite warm for January, isnt it? （表天氣）

二、引導(dǎo)詞it作形式主語的用法：

it 作形式主語，代替由動(dòng)詞不定式短語、動(dòng)詞-ing形式短語或名詞性從句所表示的真正的主語，常用結(jié)構(gòu)有：

★ Its+adj./n.+for/of sb. to do sth.

★ Its+adj./n.+doing sth.

★ Its+adj./n.+clause

★ Its+p.p.+clause

如：

(1) Its necessary for us to help each other.

(2) Its not wise of him not to accept his assistants advice.

(3) Its no use arguing with him about it.

(4) Its no wonder that he has passed all the examinations.

(5) Its been suggested that the sports meeting be put off because of the bad weather.

1. it作形式主語，替代作主語的動(dòng)詞不定式，其句型為:

（1）It be adj.（for sb.） to do sth.

此處adj.通常為描述事件的形容詞：easy， difficult， hard， necessary，unnecessary， possible， impossible， likely， unlikely， right， wrong，important， unimportant， legal， illegal， well-mannered， ill-mannered， polite， impolite， clear， obvious， certain， suitable， proper， fit， useful，useless， dangerous… 例如:

It is illegal （for a teenager） to drive a car without a license.

（2）It be adj. of sb. to do sth.

此處adj.通常為描述人的形容詞：kind， unkind， nice， rude， cruel，considerate， thoughtful， thoughtless， careful， careless， silly， foolish，stupid， clever， wise， crazy等。例如:

Its kind of you to help me with the problem.

2. it作形式主語，替代作主語的動(dòng)名詞的常見句型:

Its no good/use doing…

Its （well） worth doing…

Its （well） worth ones while doing/to do…

Its （well） worth while doing/to do…

例如: Its no use crying over spilt milk.

3. it作形式主語，替代作主語的從句常見句型:

（1）It is +n.+從句 例如:

It is no secret that the president wants to have a second term at office.

（2）It is adj.+clause

Its surprising that…（should）… ……竟然……

Its a pity/shame that…（should）… ……竟然……

例如: Its important that you should apologize to her for your rudeness.（=Its of much importance that you should apologize to her for your rudeness.）

（3）It v. sb.+clause=It is v-ing+clause

It+surprise/delight/interest/disappoint/worry／disturb／annoy／amaze／bother／concern／frighten／please／anger sb. that… 例如:

It worried me that she drove so fast.（=It was worrying that she drove so fast.）

（4）It v. （to sb.） that…=sb./sth. v. to do

（v.=appear， seem， come about， emerge， follow， chance， happen，occur， transpire， turn out， work out）例如:

It（so） happened/chanced that they were out.（=They happened/chanced to be out.）

（5）It is v-ed that…=sb./sth. is to do

（v.=say， report， think， believe， hope， expect， agree， accept， decide， determine， intend， plan， understand， know）例如:

It is said that the couple have gotten divorced.（=The couple are said to have gotten divorced.）

（6）It is v-ed that…（should）…

（v.=demand， request， require， order， suggest， advise， recommend)例如:

It is suggested that they should begin with the third question.

4. it作主語的句型例析

(1) It takes sb.…to do…（=sb. takes…to do…）某人用多長時(shí)間做某事 例如:

It took the men a week to mend our roof.（=The men took a week to mend our roof.）

(2) Its （just） （un）like sb. to do…（不）像某人做某事的風(fēng)格 例如:

It was （just） like him to think of helping us.

(3) Its（about/high） time that…should/v-ed…是該做某事的時(shí)候了 例如:

Its （about/high） time that we should take action.

(4) Its the x-th time（that）…h(huán)ave v-ed…第幾次做某事了 例如:

Its the third time that he has failed the driving test.

(5) It is/has been…since…continuous v-ed（延續(xù)性動(dòng)詞）某動(dòng)作已有多長時(shí)間不發(fā)生了 例如:

Its 10 years that he lived here.

(6) It was （not）…before…過（不）了多長時(shí)間某動(dòng)作發(fā)生了 例如:

It was not long before they arrived.

鞏固練習(xí)：

從A、B、C、D四個(gè)選項(xiàng)中選出可以填入空白處的最佳選項(xiàng)。

1. ——____ that you are doing these days?

——Nothing.Im just playing some computer games at home.

A. What is it B. What it is C. What is D. What are

2. ——____ that you came here yesterday?

——By train.

A. How is itB. How was it C. How it isD. How it was

3. ——Steven has got the first prize in the math contest.

——____ is no wonder that he looks so happy.

A. It B. As C. There D. That

4. ____ being Sunday, the library is closed.

A. That B. It is C. It D. This

5. ____ is reported that he got seven gold medals.

A. That B. As C. It D. This

6. ____ that you didn't know the river Thames.

A. It's a pity B. What's a pity

C. That's a pity D. There's a pity

Key:1.A 2.B 3.A 4.C 5.C 6.A