抛向地面的乒乓球上下弹跳几次后停下来，说明乒乓球的________能减少了，减少的那部分能量转化成了________能。
机械；内
因有结石，可加排石药物
A．王不留行、赤药
B．芒硝、大黄
C．大黄、川芎、牛膝
D．厚朴、枳实
E．槟榔、沉香
Tom with his friends _______ swimming this afternoon.
[ ]
A. is going
B. are going
C. is going to go
D. are going to go
