A:very much
B:too much
C:much too
D:so many
小丽用照相机对某同学进行拍照,拍出的底片如图甲所示,若相机的焦距不变,要使底片的像如图乙所示,则( )
某一行星有一质量为m的卫星,已知卫星的轨道半径为R,周期为T,万有引力常量为G.求: