题目【填空题】物理层描述的媒体接口特性有: _______、_______、 _______和_______【填空题】物理层描述的媒体接口特性有: _______、_______、 _______和_______题目解答答案["机械特性[1]","电气特性[2]","功能特性[3]","过程特性"]