three R's背环threenum.三n.三；三个adj.三个的three set space diversity三重空间分集Three Gorges-Gezhou Dam三峡-葛洲坝水利枢纽Three layers of structure三层结构three address instruction三地扯指令three-electrode furnace三极电炉three-axis rotary table三轴转台three dimensional warfare海陆空联合作战; 主体战争three phase fluidized bed[化] 三相流化床three figurative cultures三喻文化three-meter springboard3米跳板