Question

英语句子成分划分：下面句子哪个是主语补足语？

What appear to be large windows in the second storey are glass heat collector.
哪是主句？主语补足语是哪个？麻烦帮我把句子成分划分一下啦，谢谢大家！

Answer 1

What are glass heat collector 是主句
in the second storey是状语
What appear to be large windows是主语从句
appear是从句里的谓语
to be large windows和appear 组成系表结构

追问

为什么to be large windows和appear 组成系表结构？？

Answer 2

What appear to be large windows in the second storey是主语，are glass heat collector是系表结构。

Answer 3

what appear to be large windows in the second storey 是主语从句，主语从句做主语，主语从句，在此处，是名词成分。are,就是谓语了。最后的就是个形容词修饰的名词作宾语了。