The best examples are public utilities in markets such as electricity, water, natural gas, and sewage.

它的最好例子是市场中电力、水、天然气和污水等公用事业。

In this case, as heavy water Natural water, does contain a small proportion of the heavy variety but water enriched with the stuff is distinctive.

在这种情况下， 作为重水天然水，确实含有一小部分重水， 但富含这些物质的水是与众不同的。