Electricity, gas and water were considered to be natural monopolies.

电 、 煤气和水垄断经营过去被认为是自然而然的.

Say virtual urban-water markets within natural monopolies can be unlocked, rewarding frugality, efficiency and innovation.

指出，可以放开带有自然垄断性的虚拟城市用水市场，鼓励节约、效率和创新。