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

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

1. A.
   as
2. B.
   which
3. C.
   where
4. D.
   that

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