低压导线的截面积主要根据用电设备的（）来选择。 ["工作电压","工作电流","功率","大小"]
What three in combination are factors that can cause four-wave mixing in fiber-optic cables？（） [" low optical powe"," high optical power"," few optical channels"," many optical channels"," low chromatic dispersion"," high chromatic dispersion"," too much power differential in the optical channel"]
25T型客车电空制动集成板上安装的Dg20滤尘器采用（）滤芯。 ["毛毡","铜网","粉末冶金","缕棕"]
What is the maximum number of ARCn processes that can be defined using the initialization parameter LOG_ARCHIVE_MAX_PROCESSES？（） ["1","5","10","15","Depends on system memory resource"]
兴奋时产生舒张支气管平滑肌效应的主要受体是（） ["α受体","α1受体","β1受体","β2受体","M受体"]
变电器油每年都要取样测试，一般的试验项目为（），（）及（）。
