设物体A从点(0，1)出发，以速度大小为常数v沿y轴正方向运动，物体B从点(－1，0)与A同时出发，其速度大小为2v，方向始终指向A，任意时刻B点的坐标(χ，y)，试建立物体B的运动轨迹(y作为χ的函数)所满足的微分方程，并写出初始条件．
if two atoms of element A react with three atoms of element B, what is the chemical formula for the resulting compound?Name the following two molecules.Name the following molecules:Which of the following pairs of elements is most likely to form an ionic compound? a. magnesium and fluor...