8. Bolts and nuts should be able to be matched. When bolts and nuts are actually matched, the nuts should be screwed to the bottom, and there is no peeling off of the bolt thread.
8. Bolts and nuts should be able to be physically matched. When matching bolts and nuts, the nuts should be tightened to the end, and there should be no peeling of the coating on the bolt threads.
8. Bolts and nuts should be able to match. When the bolt and nut are actually matched, the nut should be screwed to the end, and the bolt thread has no phenomenon of falling off a piece of coating.