流动阻力的大小与流体本身的物理性质、（）及壁面的形状等因素有关。
A．流速
B．流动状况
C．流量
D．运动黏度
参考答案：B
He always devotes his time to helping children with their studies rather than ____ games on computer. [ ]
A. play
B. to play
C. plays
D. playing
水不溶性半合成高分子囊材是( )。
A．明胶B．乙基纤维素C．聚乳酸D．β-CDE．枸橼酸
