Therefore，if the Earth began as a superheated sphere in space, all the rocks making up its crust may well have been igneous and thus the ancestors of all other rocks.

(特殊结构may well have been——可能是)

因此，如果地球开始时是太空中一个过热的球体，那么所有组成地壳的岩石都可能是火成的，因此成为所有其他岩石的祖先。

解析：

主句：all the rocks may well have been igneous and thus the ancestors of all other rocks

从句1：if the Earth began as a superheated sphere in space

从句2：making up its crust

主句中两个宾语部分igneous和the ancestors of all other rocks并列

从句1作为条件状语从句，修饰主句

从句2非谓语动词后置修饰主句中的主语rocks

名词性从句 主语从句 宾语从句 同位语从句

引导词 (what/how/that/why/whether)

结构 主语从句

what+VO=n. for eg

what+SV=n. What you said is right.

形式宾语 Make it possible for sb.to do ?

that/how/why/whether+SVO=n.

That the ancestors of birds are dinosaurs is known.It is known that the ancestors of birds are dinosaurs.(形式主语居多)

形式主语和强调句的区别

形式主语 It + v + (that +SVO)=n.

n.=it

强调句 It is/was + A + that + B

SVO=A+B

而且通常情况下 It is/was……是强调句

同位语从句

同位语的实质 n1,n2—n1=n2

S,n,VO.=S,引+svo,VO

前面的成分不应当在后面充当成分。

The fact, that the ancestors of birds are dinosaurs, is known.

可接同位语的名词多为抽象名词，例如：view/idea/suggestion/fact/reason/conclusion……

同位语和定语从句的区别

同位语的句子中，前面的成分不应当在后面充当成分。

The fact, that the sun is round.

定语从句中，引导词充当成分。

The book, that you bought for me. “that”充当宾语。