高中英语语法解析2 (6-1)

第二章 “It”用法及其句型和固定搭配讲解

　　"It" 用法及其句型和固定搭配，是高中英语语法的重点、难点，又是近几年高考的热点，因此应给予充分的重视，现将it用法归纳如下：

　　一、It用作实词

　　表达以下概念:指代前文提到的事物，前文中的this, that；替代前文中的内容；指代一位性别不明的小孩或未知的人；指代未指明但谈话双方都知道的那件事；指代时间、天气、气候、距离等自然现象……

二、It用作形式主语

　　替代作主语的从句、动词不定式、动名词，而把真正作主语的从句、动词不定式、动名词置于句尾。

It 作形式主语的常见句型：

1. 代作主语的动词不定式，其句型为

(1) It be adj. (for sb.) to do sth.

此处adj. 通常为描述事件的形容词：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 It is illegal (for a teenager) to drive a car without a license.

(2) It be adj. of sb. to do sth.

此处adj. 通常为描述人的形容词：kind, unkind, nice, rude, cruel, considerate, thoughtful, thoughtless, careful, careless, silly, foolish, stupid, clever, wise, crazy.

例 It's kind of you to help me with the problem.

(3) It替代作主语的动名词的常见句型

It's no good/use doing…

It's (well)worth doing…

It's (well)worth one's while doing/to do…

It's (well)worth while doing/ to do

例 It's no use crying over spilt milk.

2. It替代作主语的从句常见句型

(1) It is + noun +从句

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

(2) It is adj. +clause

It's surprising that… (should)………竟然……

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