Zhouqu Gansu was attacked by such a terrible mud-rock flow few residents had ever experie

问题补充：

Zhouqu, Gansu was attacked by such a terrible mud-rock flow few residents had ever experienced before.

A. as

B. which

C. where

D. that

答案：

(答案→)A. as

B. which

C. where

D. that

解析：考查定语从句，先行词为a terrible mud-rock flow，从句中few residents had ever experienced后缺少宾语，因为先行词前有such，所以后应用关系代词as,选A。