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.

1. that flourished at the same time as the civilizations

2. that had flourished at the same time as had the civilizations

3. that flourished at the same time those had

4. flourishing at the same time as those did

5. flourishing at the same time as those were

用排除法可以得到A答案，但是关于其语法结构有些疑问：

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

是指civilization at the same time as the civilizations? 还是flourished at the same time as the civilizations?

1. 如果指civilization的话怎么不用a flourished ancient civilization at the same time as the civilizations这样更加简洁

2. 如果指flourished的话怎么不用flourished at the same time as the civilizations did，因为比较时如果从句中有动词的话用do/does/did来代替。

谢谢各位大侠赐教

关于这个指代曾经困扰了很久，现在稍微比以前清楚一些，就把我知道的部分说说吧。

1。是指flourished at the same time as the civilizations。

   划线部分及后面全部都是用来修饰前面一个civilization，构成同位语；

2。用经典的apple例子来解释，

   I eat apple fater than you（主句带宾语，you有修饰apple或者I的歧义，需要补助动词do来消除歧义）；

   I eat fater than you（主句不带宾语，you只能和I对应，没有歧义，不需要补助动词）

   这里flourished也属于第二种不带宾语的情况，所以不用补出助动词。

以上是我到现在为止的理解，似乎还能解释得通。。。open to discuss

I  got  it, thanks!!!!