翻了论坛，没有弄懂这两道题，请NN指教！

mongmong

请看这个贴：

http://forum.chasedream.com/GMAT_SC/thread-537203-1-1.html

mongmong

好吧我还是没有全部弄懂：为什么８９题里没有省略动词ｄｏ（且前后动词一样，时态一样）？

OG 85:
alt deposits and moisture threaten to destroy the
Mohenjo-Daro excavation in Pakistan, the site of an
ancient civilization that flourished at the same time
as the civilizations in the Nile Delta and the river
valleys of the Tigris and Euphrates.
(A) that flurished at the same time as the
civilizations
(B) that had flourished at the same time as had
the civilizations
(C) that flourished at the same time those had
(D) flourishing at the same time as those did　（Ａ）
(E) flourishing at the same time as those were

89:
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 （Ｂ）
(E) to maintain dirt roads costs twice as much as for paved roads

mongmong

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