泵的流动损失包括（）损失。
A.轴封漏泄
B.圆盘摩擦
C.旋涡阻力
D.轴承摩擦
参考答案：C
. —I have to get to the post office by six o’clock, but it is almost six now.
— . This clock is fifteen minutes fast.
A．That’s too bad
B．Sounds good
C．Sure, you can
D．Take it easy
插桩流水线上，每一个工位所插元器件数目一般以（）为宜。
A.10~15个
B.10~15种类
C.40~50个
D.小于10个
