请教一道OG上的题目，谢谢各位XDJM~~

solotomb

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 teh civilizations
D. flourishing at the same time as those did
E. flourishing at the same time as those were
答案是A，我的疑问是为什么civilizations后面不用补个did之类的，ETS给出的对于D和E的错误解释中还提到了did和were是awkward and unnecessary的。。。疑惑啊，什么时候要省略谓语呢？？
谢谢大家解惑~~
（上题为OG12  673  第85题）

vvccyy

我也很疑问这道题，想来想去，一般需要补出谓语的时候，是怕比较的对象会跟原来句子的宾语产生歧义。比如：
I eat more apple than you do我吃的苹果比你多, I eat more apple than you 我吃苹果比吃你多，就不对了。这里补补补补都没有歧义，反正后面也没有宾语，所以就不用补了。
至于D、E，特地去翻了OG：
D、Plural pronoun those cannot refer to the singular civilization and thus lacks a referent; did is awkward and unnecessary.
E、Plural pronoun those cannot refer to the singular civilization and thus lacks a referent; were is awkward and unnecessary
都说的是unnecessary,就是没有必要补出来的意思

solotomb

有道理，谢谢LS~~