it的用法

It的用法

一.用作代词

代词it主要指代前面（或后面）出现的单数名词或分句所表示的某些东西或情况、抽象事物、婴儿、也可指代性别不详孩子或身份不明的人。除此之外还可以指代时间、天气、距离、速度等抽象名词。

1.上文提到的某系东西

eg. Look at the bird. It always comes to my window.

2.抽象事物

eg. I tried my best to persuade him, but it didn’t help.

3.性别不详的孩子。

eg. The baby is crying. It might be hungry

4.时间、日期、天气、环境、距离、速度等

eg. ---What day is it today?

---It is Sunday.

---How far is it to China?

---It is 800 kilometers.

二．作形式主语

It做行主而把真正的主语置于句子后面是为了使句子平衡。It可替代后面的不定式、动名词、主语从句等。该用法通常用于一下句型：

1.”It is +adj./n./v+ing./p.p.+ that….”.适用于这个句型的动词有say, announce, decide, learn, know, report, hope, believe, expect, suggest等。适用于此句型的名词有idea, belief, dream, pity, wish, fact, wonder, problem, pleasure等。适用于此句型的形容词有clear, well—known, important, necessary, strange, urgent等。

Eg. It is a pity that I can’t go with you.

It’s necessary that children should learn some knowledge of road safety.

注意：it作形式主语代替主从时，要注意它和as 引导的定从的区别，试比较：

A: It was reported that the US was under the terrorist attack.

B: As was reported, the US was under the terrorist attack.

2.“It is+adj./n.+ to do”

Eg. It is my wish to learn a foreign language well.

3. It is +adj. + for/of + to do. for前面的形容词常常与事物的特征有关，而of前面的形容词常与人的性格特点有关。

Eg. It is too heavy for me to lift up the big box.

It is stupid of you to laugh at that guy.

4. It is + n./adj. + v+ing. 这类名词或形容词不太多，主要有waste, no good, no use, useless, no

point, worthwhile, 等。

Eg. It is no use trying to persuade me into giving up smoking.

5.It doesn’t matter/It makes no difference…..

Eg. It makes no difference whether he is present or not..

6.It appears/seems/happens (to sb) that…好像/似乎/碰巧…

Eg. It appears to me that he is fond of collecting stamps.据我所知，他好像喜欢集邮

三．用作形式宾语

1.当动词不定式、动名词、或从句在句中充当宾语且其后带有宾补时，习惯上要在宾补前使用一个没有具体意义的形宾it，而将真正的宾语移到补足语的后面，构成“V. + it + OC+to do/v +ing/从句(常将该句型称之为6123结构)

Eg. I think it no good going there now.

The headmaster has made it clear that the meeting will not be put off.

6123结构：6指主句中6个常用的动词，即think, believe, make, find, consider, feel;

1指的是形宾it

2指的是宾补的两种形式——形容词和名词（短语）

3指的是真正的宾语的三种形式——不定式短语、动名词短语和that引导的宾语从句。

2. It作形宾时其后没有adj. 或n.作宾补的情况（近几年高考常涉及）

Eg. I hate it when people talk with their mouths full.

I’d appreciate it very much if you would help me with it.

该用法中的动词经常是表示“喜怒哀乐”的动词。如：enjoy, like, dislike, love, hate, prefer, appreciate等

四．It构成的强调句型

强调句型“it is/was + 被强调的部分+that/who + 其他成分”用来强调主语、宾语或状语等。That 只起连接作用，不作成分，但不能省略。有时强调的部分比较特殊，如主从、状从、名词、不定式、动词-ing的复合结构。

Eg. It was in the library that I saw her yesterday.

It was when I returned that she left the meeting room.

注意：1.要注意it 所构成的强调句型和它代表时间、距离、温度、自然现象、具体事物或人物等构成的各种句型的区别。如: It was on March 1 that I had my hair cut.

It was March 1 when I had my hair cut.

2.采用“还原法”来判断强调句型

3.强调句型的三种形式：A: 一般疑问句形式：Was/Is it + 强调部分+ that/who +其他成分

B:特殊疑问句形式：特殊疑问词+is/was+ it +that/who +其他成分

C: not….until…的强调句形式：It is/was not until +被强调成分+

that+其他成分