对于非圆形管,当量直径等于四倍的()除以润湿周边。
A.流通截面积;
B.表面积;
C.流动体积;
D.流通体积。
参考答案:A
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1._____2._____3._____4._____5._____
如果一次函数y=kx+b的图像经过第一、三、四象限,那么[ ]
A.k>0,b>0
B.k>0,b<0
C.k<0,b>0
D.k<0,b<0