Topic: how to distinguish the quality of aluminium lighti

First, two strips are observed to see if the nodes of the two strips are on both non-commission nodes and have no load. If the above two points are met, the two subts are zero. Second, determine if the node of the two strokes is not a common line. Third, for the three stroke, if a three stroke node is loaded on a stroke, the two strokes are on a straight line, the third stroke is zero. ...