one SC question

bmusculus

Salt 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 flourished 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
e. flourishing at the same time as those were

answer is a. but, should it be ....as DID the civilizations, so the verb here can be omited?

thanks

susieshen

建议你看看比较的庖丁解牛之后就明白了

这里面省略动词不会引起歧义

http://forum.chasedream.com/dispbbs.asp?BoardID=23&ID=103101&replyID=&skin=0