three pair三对threenum.三n.三；三个adj.三个的three- phase three- wire三相三线制three drum boiler low-head低头三锅筒锅炉three phase electric railway三相电气铁道three yang meridians of hand手三阳经three dimensional parametric维参数化Three planes ultrasonography三平面正交超声three-component fancy yarn三组分花式线three phase four wire system三相四线制three aspects of landscaping景观三元论three-dimensional greening立体绿化