As is known to all, one of the many benefits of ________ adventure travel is teaching children how to cope with ________ unexpected.

A．the; /

B．/; an

C．the; the

D．/; the

换铺无缝线路时，在线路作业中发现有胀轨预兆时，应（）。

A.立即停止作业

B.立即查找原因

C.立即整改

D.立即报告有关部门