GWD-10-Q3

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.

1. each a roof of poles and arrowweed

2. each a roof of poles and arrowweed that are being

3. with each being a roof of poles and arrowweed

4. with roofs of poles and arrowweed to be
5. with roofs of poles and arrowweed that are

答案是A，我选了E，可能理解有误，正确答案是什么含义啊？