r explaining the operation of a wafer and a polishing ring wheel of this polishing apparatus; [0171]FIGS. 19A to 19C are views of a polishing ring wheel of a polishing apparatus according to an 11th embodiment, where FIG. 19A is a sectional view, FIG. 19B is a plan view, and FIG. 19C is a sectional view for explaining the operation when using the polishing ring wheel; [0172]FIGS. 20A and 20B are v