On the basis of the original plan of “four vertical and four horizontal” main structure, the existing railways are fully utilized to form a high-speed railway network with “eight vertical and eight __________________________as the framework, regional connection lines and intercity railway as supplement. 在原有“四纵四横”主体结构规划的基础上，充分利用现有铁路，形成“__________________________”为主框架、地区铁路、城际铁路为辅的高速铁路网。
A、horizontal railway transport channels 八纵八横向铁路运输通道
B、4 main lines running east-west 四横主干线
C、4 main lines running north-south四纵主干线