高二英语第四单元Grammar.pptVIP

* * Unit 4 我们知道在句子中起名词作用的句子叫名词性从句。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，介词宾语等，因此根据它在句中不同的语法功能，名词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。 Read the two sentences firstly. What it was to become was uncertain until between 4.5 and 3.8 billion years ago… …it was not clear whether the shape would last or not. 通过观察，我们发现两句当中划线部分的句子都在复合句中起名词的作用，因此称之为主语从句。 主语从句在复合句中作句子的主语。引导主语从句的词有从属连词that, whether, if；连接代词who, whoever, whom, what, whatever, whose, which；连接副词when, where, how, why等。 观察下列例句，指出其中所包含的主语 从句及引导词: 1. What is needed for a long trip is careful preparation. 该句中主语从句是 __________________ _________，引导词为 _____。 What is needed for a what long trip 2. That Jay Zhou will come to my city excites everybody. 该句中主语从句是 _________________ ______________，引导词为_____。 3. Whether we will travel abroad or not has not been decided. 该句中主语从句是 _________________ __________________，引导词为 _________。 That Jay Zhou will Whether we will come to my city that travel abroad or not whether 4. Whoever knows the secret mustn’t tell others. 该句中主语从句是__________________ ______，引导词为________。 5. It remains a puzzle why dinosaurs died out suddenly long time ago. 该句中主语从句是_________________ _______________________，引导词为 _____。 Whoever knows the whoever why dinosaurs died why secret out suddenly long time ago 【观察总结】 通过分析上面例句，同学们可能会发现上面第5句中的主语从句似乎比较隐蔽。其实，这也是主语从句的一种呈现方式，即：当一个句子主语过长时，可以用it作形式主语，而把真正的主语或主语从句后移至句子末尾，以保持句子的平衡。注意观察下列例句中的划线部分： It is not clear how the accident happened. It is not hard to understand why he did so at that time. It is a pity that you should have made such a careless mistake. It is reported that more than thirty deaths were caused in the accident. 不难看出，虽然上面例句中都用it作形式主语，但句子结构却不尽相同。现将常见的由it作形式主语的句型总结如下： 1. It be + n. + that从句 2. It be + adj. + that从句，常见此类形容 词有：important, necessary, clear, certain, natural, strange, obvious, likely, impossible, possible等。 3. It+不及物动词+that从句 It seems / appears ... that ... 似乎…… It happened (to sb.) that ... （某人）碰巧…… 4. It + be + 过去