题目

All around us buildings shook. We decided to leave the town. We stopped once we had left the buildings behind us. The carts(马车) were moving on opposite directions, though the ground was perfectly flat, and they wouldn't stay in place even with their wheels blocked by stones.    In addition, it seemed as though the sea was being sucked(吸) backwards, as if it were being pushed back by the shaking of the land. Certainly the shoreline moved outwards, and many sea animals were left on dry sand.    Behind us were frightening dark clouds that opened up to show fire--like lightenin我国兼跨地势第一、二级阶梯的省级行政单位是（ ）A．山西B．湖北C．四川D．河北