基站采用自建房时，走线架安装高度通常为（）mm ["2000","2200","2400","2600"]
走线架整体应保持水平，垂直偏差不大于（） ["1‰","1.5‰","2‰","2.5‰"]
走线架、凹钢加固点或支撑点距离应为（）米 ["1—1.5","1.5—2","2—2.5","2.5—3"]
一根凹钢的长度为（）米 ["1.5","2","2.5","3"]
机柜垂直偏差度应小于（）mm ["1.5","2","2.5","3"]
进行暗场观察，金相显微镜必须具备（）；（）；（）。
