Unit 1 A Land of DiversitySection IV Grammar学习目标：熟记虚拟语气中与现在事实相反的 if 条件句及 I wish 加从句的用法。学习重点：熟记并理解虚拟语气，并能正确完成练习题。学习难点：学以致用，在文章中会使用虚拟语气。学习过程 生命课堂—互动探究语法知识—预习探究名词性从句在句子中起名词作用的句子叫名词性从句 (Noun Clauses)。 名词性从句的功能相当于名词词组, 它在复合句中能担任主语、宾语、表语、同位语等，因此根据它在句中不同的语法功能，名词性从句又可分别称为主语从句、宾语从句、表语从句和同位语从句。一、引导名词性从句的连接词可分为三类：连接词：that, whether, if (不充当从句的任何成分连接代词：what, whatever, who, whoever, whom, whose, which, whichever连接副词：when, where, how, why, wherever不可省略的连词：1. 介词后的连词2. 引导主语从句和同位语从句的连词不可省略。That she was chosen made us very happy.We heard the news that our team had won.比较：whether 与 if 均为"是否"的意思。但在下列情况下，whether 不能被 if 取代：1. whether 引导主语从句并在句首2. 引导表语从句 3. whether 从句作介词宾语4. 从句后有"or not" Whether he will come is not clear.大部分连接词引导的主语从句都可以置于句末，用 it 充当形式主语。It is not important who will go.It is still unknown which team will win the match.二、连接词 that-名词性从句11、that 只起连接主句和从句的作用，在从句中不担任任何成分，本身也没有词义。主语从句：That he is still alive is sheer luck.宾语从句：John said that he was leaving for London on Wednesday. 表语从句：The fact is that he has not been seen recently. 同位语从句：The fact that he has not been seen recently disturbs everyone in his office. 形容词宾语：I am glad that you are satisfied with your job.2、that-从句作主语通常用 it 作先行词，而将 that-从句置于句末，例如：It is quite clear that the whole project is doomed to failure. It's a pity that you should have to leave. 用 it 作形式主语的 that-从句有以下四种不同的搭配...
