Period Four　Grammar-Noun clauses as the subject

阅读以下教材原句，仔细观察黑体部分并补全空格。

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

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

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

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

5．Why they suddenly disappeared still remains a mystery.

6．So whether life will continue on the earth for millions of years to come will depend on whether this problem can be solved.

1．以上黑体部分在句中作主语。

2．1句中的what在从句中作表语；3句中的what在从句中作主语。

3．2,6句中的whether意为：是否。

4．4句中It是形式主语，真正的主语是后面that引导的从句。

5．5句中why在从句中作状语。

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、地点、方式、原因状语等成分。

(1)What we need is more water.(连接代词what在从句中作need的宾语)

我们需要的是更多的水。