Period 6 名词性从句：主语从句

学习目标： 1、理解并掌握本节主语从句的规则及用法。2、完成练习。

观察下列从Reading中选取的句子，并说出其引导的从句在主句中充当的成分及引导词的功能。

①What it was to become was uncertain until between 4.5 and 3.8 billion years ago when the dust settled into a solid globe.

②The earth became so violent that it was not clear whether the shape would last or not.

③What is even more important is that as the earth cooled down，water began to appear on its surface.

④It was not immediately obvious that water was to be fundamental to the development of life.

⑤What many scientists believe is that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans and seas.

自我总结]　 1.引导词what/whether/that引导的从句在句中均可作 语。

2．what引导从句，并在从句中充当表语( )、主语( )、宾语( )。

3．that引导从句，但在从句中不充当成分，也无意义( )。

4．whether引导从句，在从句中不充当成分，但是有"是否"的意义( )。

主语从句

1．主语从句的引导词

类别 例词 说明 从属连词 that，whether 两者在从句中均不作成分，只起连接作用；that无实义，whether表示"是否"。 连接代词 who，what，which，whoever，whatever等 在从句中作主语、宾语、表语、定语等成分。 连接副词 when，where，how，why等 在从句中作时间、原因、地点、方式状语等成分。 Who will do it doesn't matter.(连接代词who在从句中作主语) 谁做这件事都没有关系。

What we need is more water.(连接代词what在从句中作宾语) 我们需要的是更多的水。

2．it作形式主语