[問題]大全987-244

[Alycia]

244. Dirt roads may evoke the bucolic simplicity of another century, but financially strained townships point out that dirt roads cost twice as much as maintaining paved roads.(A) dirt roads cost twice as much as maintaining paved roads
(B) dirt roads cost twice as much to maintain as paved roads do
(C) maintaining dirt roads costs twice as much as paved roads do
(D) maintaining dirt roads costs twice as much as it does for paved roads
(E) to maintain dirt roads costs twice as much as for paved roads

The answer is B and I understand that it is gramatically right....but why is D wrong??

[freshmanduke]

D不平衡阿
而且it不知道是指誰?
故D錯