初中英语语法：it用作形式主语的用法

1、It would be a tragedy if anything went wrong.It would be a tragedy if anything went wrong.如果出了什初中英语语法： it 用作形式主语的用法一、基本用法当不定式、动名词、从句等用作主语时，避免头重脚轻，通常在 句首使用形式主语 it ，而把真正的主语放在句子末尾：Is it necessary to tell his father everything? 有必要把这 个切都告诉他父亲吗 ?It s no good sitting up too late. 熬夜没有好处。It is quite clear

2、that he has read the book. 很显然，他读 过这本书。It doesn t matter what he says. 他说什么没关系。二、几种特殊的形式主语用作动词 look, seem, appear, happen, occur, follow 等 的主语(后接 that 从句或 as if 从句)：It seems as if it is going to rain. 看来要下雨了。It seems that he knows everything. 他好像什么都知道。It (so) happened that I had no money with me. 碰巧

3、我没带 钱。From this witness it follows that he must be guilty. 根据 该证人的证词判断，他一定有罪。当系表结构后接有if或when引出的状语从句时，通常在系表结构前使用形式主语表示说话人对某情况的看法：It was a great surprise to me when he did a thing likethat. 他这样做使我很吃惊。么事就是一个悲剧。用于其他固定句型，如if it were not for(若不是因为)，it s time that (该了)等。三、误用形式主语的几种情形在该用 it 作形式主语的地方而误用其他词：I

4、s necessary to tell his father everything?A. it B. thatC. what D. he此题的准确答案应是 A(it 用作形式主语 )，而不能选 D。在不该用形式主语的地方而误用形式主语： must be something wrong with the machine.A. There B. ItC. He D. That此题应选A,为there be句型与情态动词must连用的情形。比较以下两组句子： is known to us all, the earth turns around the sun. is known to us all that the earth turns around the sun.A. It B. WhichC. As D. That前一句填 C，as 用以引导一个非限制性定语从句 ; 后一句填 A，it为形式主语，真正的主语是其后的 that 从句。 is difficult to persuade her to stay. is difficult is to persuade her to stay.A. It B. WhatC