求问Prep上一道语法题

seachina

Q41.
The single-family house constructed by the Yana, a Native American people who lived in what is now northern California, was conical in shape, its framework of poles overlaid with slabs of bark, either cedar or pine, and banked with dirt to a height of three to four feet.
(A) banked with dirt to a height of
(B) banked with dirt as high as that of
(C) banked them with dirt to a height of
(D) was banked with dirt as high as
(E) was banked with dirt as high as that of

这题啥意思啊，看也没看明白。正确答案是A，但为什么不选D呢？

seachina

自己顶一下

李学子

D dirt与a height of three to four feet比，错误。且banked与conical平行，意思不通