2019学年度人教版选修八Unit5A land of diversity Period4Grammar-Noun clauses学案

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,名词从句又可分为主语从句、宾语从句、表语从句和同位语从句。

主语从句的用法

一. 主语从句在复合句中作主语, 它可以位于句首, 但常见的主语从句多放在句末, 句首则用形式主语it。

1. That the earth is round is true.

= It is true that the earth is round.

2. Whether he will come hasn't been decided.

= It hasn't been decided whether he will come.

注意: 连词that, whether在从句中不担任句子成分, 只起连接作用, 不能省略 (注:if不可用来引导主语从句）

二. 用it 作形式主语的结构

(1) It is＋名词＋从句

It is a fact that ... 事实是...

It is an honor that ...非常荣幸

It is common knowledge that...是常识

(2) It is＋形容词＋从句 (多用 should)

It is natural that... 很自然...

It is strange that... 奇怪的是...

(3) It is ＋ 不及物动词＋从句

It seems that... 似乎...

It happened that... 碰巧...

It appears that... 似乎...