题目

Her husband died because of smoking last month and she (ban) her son from smoking eversince. 答案：【1】has banned/ has been banning1．未来人类在研究火星时，将要在火星上完成一系列的探究实验，比如在火星的表面将一小球以v0的初速度竖直上抛，小球在空中运动的时间为$\frac{2{v}_{0}}{g}$．若发射一颗火星的卫星，其最小的运行周期为2π$\sqrt{\frac{{R}^{3}}{GM}}$，已知火星的质量为M，火星可以视为半径为R的球体，万有引力常量为G．