A.5
B.2
C.3
D.4
A.2
B.3
C.4
D.5
A.电压
B.电流
C.电感
D.电场
A.用以补充压缩机在运行过程中消耗的润滑油
B.当机组紧急停车时向机组提供惯性运行所需要的润滑
C.当润滑油系统故障导致压缩机停车时,为压缩机惯性运行提供润滑
D.当润滑油系统故障导致压缩机停车时,为压缩机组惯性运行提供润滑
How does a consumer trade off current and future costs when selecting an air conditioner or other major appliance? How could this selection be aided by an NPV calculation?