对于不可压缩流体在管线里流动，通过各管道的（）不变。
A.质量流速
B.体积流速
C.温度
D.质量
参考答案：A, B
How could lashing gear used aboard Ro-Ro vessels be stowed when not in use?（）
A.Drape along brackets
B.Hang vertically in a sheltered area
C.Stow in bins at hatch coming side
D.All of the above
