three pair三对threenum.三n.三；三个adj.三个的Three people were present.有三个人出席。three classes and nine ranks三等九则three hundred and fifty four(=354) 三百五十四three dimension acceleration三维加速度threep- hase united action三相联动Three-dimension topography三维地形three-condition cable code三情况电缆码Three Gorges Reservior areas三峡库区three-layer slab waveguide3层平板波导three -phase fluidized bed三相流化床