曾　军　张忠良

it是高考测试的热点内容之一，它不仅可以指代时间、地点、天气、距离等，还可以作形式主语和形式宾语，同时还可以用于强调句结构中，下面就结合高考题来谈谈它的用法，希望能对同学们的学习有所帮助。

一、 it用作代词

1.it指代前文提到过的事物，可指前面刚提到的同一事物或某人。如：

I was disappointed with the film. I had expected ____ to be much better. (93NMET)

A. that B. this C. one D. it

[解析]首先让我们看that, one, it这三个代词的用法区别：it用来替代前面提到的同一事物,one作替代词,相当于“a(an)+名词”，用来代替前面出现过的“同类”事物,that用来替代前面提到的特指的事物,本题中的代词是代替上文中提到的the film，应用it，答案为D。

2.指代前一个句子的内容或情况。如：

The doctor advised Vera strongly that she should take a holiday, but ____ didnt help. (05全国卷Ⅲ)

A. it B. she C. which D. he

[解析]因为有连词but，不能用关系代词which，it用来代替上文“The doctor advised Vera strongly that she should take a holiday”这个句子的整体意义，答案为A。

3.it指代天气、时间、距离、地点、温度、自然环境等。如：

(1) ____ from Beijing to London! (93NMET)

A. How long way it is B. What a long way is it

C. How long way is it D. What a long way it is

[解析]it在此指距离，这是一个感叹句，修饰名词用what，答案为D。

(2) ——Did Jack come back early last night? (05福建)

——Yes. It was not yet eight oclock ____ he arrived home.

A. before B. when C. that D. until

[解析]it在这里代指时间，根据题干“他到家时还不到八点”，可知是when（当……时候）引导的时间状语从句，答案为B。

(3) It was some time ____ we realized the truth. (05山东)

A. when B. until C. since D. before

(4) It was not long ____ a customer who had seen him arrive dropped

in to inform him that his car was covered with bees. (05重庆)

A. when B. after C. until D. before

[解析]It is/was/will be+段时间+before从句,这一句型意为“还有……时间就……”，为否定句时，段时间只能是long一词,整个句型表达“不久……就……”,所以答案为(3)D (4)D。

(5) That was really a splendid evening. Its been years ____ I enjoyed myself so much. （05安徽）

A. when B. that C. before D. since

[解析]It+is/has been+一段时间+since从句,意为“自……以来已有多长时间了”或“自不……以来已有多长时间了”。在该句型中若since从句的谓语动词是非延续性动词,则表示从句中的动作延续多长时间了;若since从句的谓语动词是延续性动词或状态动词,则表示从句中的动作已结束多长时间了,答案为D。

二、it 作先行词，在句中充当形式主语或形式宾语，而把真正的主语或宾语如动词不定式、动名词短语、主语从句或宾语从句等移到句子后边去。