threeunitn.三单位电码threenum.三n.三；三个adj.三个的three - level inverter三电平逆变器three-gradation method三级算法three-level excitation三能级激发three hundred and ninety(=390) 三百九十three- dimension model三维建模three-level modulation三级调制three level storage mode三级存储模式three-terminal network三端网络three layer architecture三层架构three-axis integrative三轴一体化