(
课件网) Unit 4 Breaking boundaries Using language It as an empty subject Look at the sentences and answer the questions. Sentences (a) and (c) are from the reading passage. 1 What does “it” refer to in sentences (a) and (c) 2 Why does the author choose to use sentences (a) and (c) instead of (b) and (d) a But it is vital not to take any chances. b But not to take any chances is vital. c It is important to remember that Ebola doesn’t respect national boundaries. d To remember that Ebola doesn’t respect national boundaries is important. The first sentences in each group use “it” as an empty subject at the beginning of the sentences. The reason why sentences (a) and (c) are chosen is that the sentences are kept balanced and the key information of the sentences is emphasised. Now look for more sentences with this structure in the reading passage, and summarise its use in your own words. I felt it was my duty as a doctor to go there and offer my help. It is so inspiring to have colleagues like Wilton, Maisy and Alfonso, ... ..., it is absolutely essential for us all to collaborate to create a global community with a shared future of peace and prosperity. It as an empty subject It 作形式主语 通常it作为形式主语，在句中没有实际意义，只是满足语法需要，起到一个平衡句子结构，避免句子头重脚轻的作用。 概念 把下列的句子变成用it的形式主语句。 1. To say goodbye is difficult for me. It is difficult for me to say goodbye . 2. Playing too many computer games is a waste of time. It is a waste of time playing too many computer games. It is obvious that he is clever. 3.That he is clever is obvious. It as an empty subject It 作形式主语 类型 通常it代替不定时、动名词、从句充当主语，起到一个平衡句子结构，避免句子头重脚轻的作用。 类型 1. 代表不定式 (1) It + be + 形容词 + 不定式 It is difficult to translate the book. (2) It + be + 名词 + 不定式 It was her duty to clean the room. (3) It + be + 介词短语 + 不定式 It was against my principle to do that. (4) It + 及物动词 + 宾语 + 不定式 It cost 150 yuan to buy the dress. 在“It＋be＋形容词＋for/of sb.to do sth.”句型 中，如果形容词描述的是sb.，则应用介词of； 如果描述的是to do sth.就用for。 It's necessary for us to use a short wave radio to pick up the programmes. 我们用一台短波收音机收听这些节目是必要的。 It was foolish of him to give up the job. 他放弃那工作是愚蠢的。 类型 2. 代表动名词 it 代表动名词时，一般以“be + 名词”作谓语，也可以以“be + 形容词”作谓语。常限于no good, no use, useless, waste等词的后面。 It is no good/ use having a car if you can't drive. It is a waste of time watching TV It is no use asking him. 类型 3. 代表从句 It + be + ……从句，具体可以分为四种类型： （1）it + be + 形容词 + 从句 It is clear that he told a lie. （2）it + be + 名词 + 从句 It is a pity that you can't come. （3）it + 动词的被动语态 + 从句 It is said that he is friendly. （4）it + be/其他系动词 + 从句 It may seem that you’re wasting your life away. It as an empty subject It ... ...
