ECNOMICS Degree of Natural Monopoly in Different Industries 1-129 Figure 17-3 三三三 多 Perfect Natural competition monopo Mcgraw-Hilllrwin Copyright C 2001 The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill/Irwin Copyright © 2001 The McGraw-Hill Companies, Inc. All rights reserved. Degree of Natural Monopoly in Different Industries T-129 Figure 17-3