Weighing two hundred pounds       .

A．she could not move the box

B．the box could not move

C．the box was too difficult to be moved

D．the box was too heavy for the girl to move

粉体学中，用包括粉粒自身孔隙和粒子间孔隙在内的体积计算的密度称为（）

A.堆密度

B.粒密度

C.真密度

D.高压密度

E.空密度