. You had better take enough money with _________ while you ___________.

A．yourself, were shopping

B．yourself, are shopping

C．you, are shopping

D．you, were shopping

采集列检作业场概况，接发列车和扣修车辆及维修信息，并采集车辆行车事故和其他紧急情况等信息的HMIS子系统是（）。

A、站修子系统

B、运用子系统

C、轮轴子系统

D、段修子系统