. —Why didn’t you response to their greeting?  

—Sorry. I ______they ______ to me.

A．don’t realize; are waving

B．don’t realize; were waving

C．didn’t realize; were waving

D．didn’t realize; are waving

冶炼工程自动化控制系统调整及试运行时，与电气设备有关的（　）等装置均应投入运行。

A．能源介质

B．冷却系统

C．环保系统

D．润滑系统

E．保护系统