Having been attacked by terrorists, ______.[ ]

A. doctors came to their rescue

B. the tall building collapsed

C. an emergency measure was taken

D. warnings were given to tourists

下列哪项不在中国地形的第二级阶梯上？

A.秦岭 

B.呼伦贝尔草原 

C.鄂尔多斯高原 

D.巴颜喀拉山