. Not only should you get used ______ under difficult conditions but you also you pay more attention ______ your work well.

A．to work, to do

B．to working, to doing

C．to work, to doing

D．to working, to do

通信部门负责单位内部所有网络的运行维护，因此，通信部门是客户经理最主要的服务对象。（）