“二体”的英语？

“二体”的拼音为：èr tǐ...

在二体假设下, 推导了椭圆轨道上相对运动方程的近似形式.In the two - body case, the approximate equations of relative motion on elliptic orbits are derived.研究了真空熔铸法制备的锰白铜基铸造碳化铬复合材料的二体磨料磨损机理.The abrasion wear mechanism of Mn copper - nickel alloy ma...