Even slight spiraling motion in a square pipe increases the tendency of particles to be maintained in suspension. 水流在方管中稍有一些螺旋运动，将增加泥沙悬浮在水中的作用。
It is the sufficient and necessary condition that the velocities of three non-collinear points in a rigid body can determine a screw motion of the body. 这是物体上非共线三点的速度能确定此物体螺旋运动的充分必要条件。
