[语法初识]

原句感知 自主探究 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.

⑥So whether life will continue on the earth for millions of years to come will depend on whether this problem can be solved. (1)以上各句皆为主从复合句，句中黑体部分为名词性从句作主语，称之为主语从句。

(2)what引导主语从句，what在从句中作表语(句①)，主语(句③)，及宾语(句⑤)。

(3)whether引导主语从句，意为：是否(句②⑥)。

(4)可用it作形式主语，真正的主语为名词性从句(句④由that引导主语从句)。 　　

　　[语法剖析]

语法点一 定义 　　在主从复合句中充当主语的从句即为主语从句。

　　What made her happy was that she won the game in such an important match.

　　令她高兴的是在这么重要的比赛中她获胜了。

　　It is decided that the meeting has been put off till next Monday.

已经定下来将会议推迟到下周一了。