A:47
B:14
C:1
D:25
---When did the film star arrive ________America, Jane?
--- Sorry, I don't know
小球从地面上方某处水平抛出,抛出时的动能是7J,落地时的动能是28J,不计空气阻力,则小球落地时速度方向和水平方向的夹角是( )