最新真题15题第5题

For protection from the summer sun, the Mojave lived in open-sided, flat-topped dwellings known as shades, each a roof of poles and arrowweed supported by posts set in a rectangle.

请问划线部分应该如何理解它的语法结构?

each引导独立主格结构。

可以理解为：each (has) a roof of poles and arrowweed supported ...其中supported引导过去分词做定语修饰a roof of poles and arrowweed。在独立主格结构中省略谓语动词。