_____ for the breakdown of the school computer network,Alice was in low spirits. [ ]

A. Blaming      

B. Blamed              

C. To blame            

D. To be blamed

一颗绕地球做匀速圆周运动的人造卫星，离地高度为h．已知地球半径为R，地球表面的重力加速度为g．求人造卫星绕地球的运行周期T．