在机器设备评估中，重置核算法是一种最为普遍适用的方法。 ( )
参考答案：错
若直线l：mx-y=4被圆C：x2+y2-2y-8=0截得的弦长为4，则m的值为______．
Cultured pearl is formed by ______.
A．insertion of a pearl into a live mollusk
B．an oyster into which a piece of grit has been placed
C．putting in a live mollusk
D．placing a bead into culture
