题目

When the Audet family turns on the lights at Blue Farm, they are using electricity that comes from cows—cow manure (粪肥), to be specific.Cows produce a lot of wastes. One cow can create 30 gallons of wastes each day. Now imagine t he output of over 1,000 cows at Blue Farm. That’s really a big amount.When farmers clean their barns, they put the wastes in a big heap, and spread some of them on their fields for fertilizer(肥料). But now places like Blue Spruce Farm have a new way of using cow wastes. They use them to produce electricity.Here’s how it works: A big machine moves 2．现有高锰酸钾、二氧化锰、过氧化氢、氧化汞四种物质，下列有关叙述正确的是（　　）A．都含有氧气B．都含有氧原子C．都含有氧分子D．都含有氧元素