Unit 4 Section 4 Grammar—it作形式主语-【赢在微点】轻松课堂2023-2024学年新教材高中英语选择性必修第二册（外研版）

Section 4　Grammar—it作形式主语 课前观察自主领悟 语法图解 观察句子 1.It is said that he was a famous writer. 2.It requires patience to teach children. 3.It is not easy for us to master a foreign language. 4.It is stupid of you to make such a mistake. 5.It is a pleasure to be with you. 6.It is no use explaining it to him. 我的领悟 it作形式主语时没有具体的意义,而只是帮助把真正的主语移到句子后部去,使句子显得平稳一些。it作形式主语时,可以代替三种形式:不定式、动名词和主语从句。 语法课堂高效学习 一、it代替不定式短语 常用于下列句型中: (1)It+be+形容词+(for/of sb.) to do sth. ①It is difficult for a foreigner to learn Chinese. 对于一个外国人来说,学习汉语是困难的。 (it作形式主语, 代替不定式短语to learn Chinese) ②It is not right to use these places as rubbish dumps. 把这些地方用来倒垃圾是不对的。 (it作形式主语, 代替不定式短语to use these places as rubbish dumps) 注意:It be+形容词+for sb. to do sth.与It be+形容词+of sb. to do sth. 如果句型中的形容词描述的是sb.的品质、品格,在逻辑上可以作sb.的表语,则sb.前应用介词of,否则就用for。 ③It􀆳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有必要的。 ④It􀆳s important for us to learn English well. 学好英语对我们来说是重要的。 ⑤It􀆳s kind of you to help me. 感谢你对我的帮助。(=You are kind to help me. ) ⑥It was foolish of him to give up the job. 他放弃那工作是愚蠢的。(=He was foolish to give up the job.) (2)It+be+名词+to do sth. It is everyone􀆳s duty to obey the law. 遵守法律是每个人的义务。 (it作形式主语, 代替不定式短语to obey the law) (3)It takes sb. some time to do sth. 做某事花了某人……时间 It took them a year to build the bridge. 建这座桥花了他们一年的时间。 (it作形式主语, 代替不定式短语to build the bridge) (4)It􀆳s up to sb. to do sth. 做某事是某人的职责或义务 It􀆳s up to teachers to teach students well. 教好学生是老师的职责。 二、it代替动名词短语 动名词作主语用后置形式的情况远不及不定式那么普遍,常限于no good, no use, useless, waste等词的后面。 ①It is no good/use having a car if you can􀆳t drive. 如果你不会开车,有车也没用。 (it作形式主语,代替动名词短语having a car) ②It is a waste of time watching TV. 看电视是浪费时间。(it作形式主语,代替动名词短语watching TV) 三、it代替主语从句 (1)这个主语从句可以用连词that引导,也可以用连接代词或连接副词引导。 ①It was clear that they had no desire for peace. 很清楚他们没有和平的诚意。 (it作形式主语,代替主语从句that they had no desire for peace) ②It is doubtful whether she will be able to come. 她是否能来还很难说。 (it作形式主语,代替主语从句whether she will be able to come)