宇航员站在某一星球距离表面h高度处，以初速度Vo沿水平方向抛出一个小球，经过时间t后小球落到星球表面，已知该星球的半径为R，引力常量为G，求：

1.该星球表面的重力加速度g大小？ 2.小球落地时的速度大小？ 3.该星球的质量？

I've tried very hard to improve my English. But by no means         with my progress.      

A. the teacher is not satisfied      

B. is the teacher not satisfied      

C. the teacher is satisfied      

D. is the teacher satisfied