three Ps三Pthreenum.三n.三；三个adj.三个的three-layer films三层膜three major systems三大体系three-eighth rule八分之三法three-layer ocean三层海洋three-factors fit三因素匹配three-step timing三级调速three-demarcation三标度法three level voltage三电平Three media manikin三层介质人体模型three axes pedestal三轴天线座