Norway is at _____ top of the list, and ______ other top five countries are: Iceland, Sweden, Australia, the Netherlands.

A．/ ; the

B．the ; /

C．the ; the

D．a ; /

当牵引通风机过流造成自动开关断开后，其主触点断开对应牵引通风机的供电电路，辅助触点将故障信号送到（）。