一、英语句子结构的原则
1、谓动单一性原则 在一个句子里，有且只有一个谓语动词。
2、主句单一性原则 在一个句子中，有且只有一个主句。(从句可以有若干个)
二、三大从句
1、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。
Example
It is generally accepted that the single super continent known as Pangaea indeed existed, that Pangaea subsequently broke apart into two giant pieces, Gondwanaland in the south and Laurasia in the north, and that the continents attached to the various crustal plates separated and drifted in various directions.
人们普遍接受，Pangaea 以一个特别大的陆地形式存在，后来他被分为两个大块，在南边的Gondwanaland 和在北边的Laurasia，他和那些在不同地壳上的大陆分开了并且向不同方向上漂移。
**如何找出复杂句中的谓语?
先找引导词，然后去掉随后的动词，还有动词的话，这个动词就是谓语。
