【正确答案】 A

【答案解析】 [听力原文]
   M: Professor, in the nineteen seventies, scientists predicted that the world's oil reserves would have all been used up by the beginning of the twenty-first century.
   W: VThose predictions were highly exaggerated. However, in a hundred years' time at the present rate of consumption, we will have used all the available oil resources. Therefore, we need to find clean renewable fuels, especially for automobiles.
   M: What other fuels are being developed?
   W: We're working on alternative sources of energy such as biodiesel, solar energy, electricity, and hydrogen.
   M: What will we be filling our car tanks with in twenty years' time?
   W: According to the U.S. National Engineering Academy, by 2024, half of all vehicles will he running on part electricity and part gasoline. They also predict that by 2038, all the new cars produced in the U.S. will use hydrogen.
   M: That's a big change in a relatively short period of time. Can you tell us more about this hydrogen fuel?
   W: Certainly. Scientists have long been fascinated by the appeal of hydrogen fuel ceils. Since these devices use electrochemical reactions to generate electricity from hydrogen, emitting only heat and water in the process, they offer a particularly green source of power, especially for vehicles. What has not been so fascinating, however, is how to make hydrogen fuel cells practical.
   M: You mean those hydrogen fuel cells are still in the developmental stage?
   W: Yes, and there are setbacks and detours. In 2009, Steven Chu, then the U.S. Secretary of Energy told an interviewer that in order for hydrogen fuel-cell transportation to work, "four miracles" needed to happen. First, scientists had to find an efficient and low-cost way to produce hydrogen. Second, they had to develop a safe, high-density method of storing hydrogen in automobiles. Third, an infrastructure for distributing hydrogen had to be built so that fuel-cell vehicles would have ample refueling options. Fourth, researchers had to improve the capacity of the fuel-cell systems themselves, which were not as durable, powerful, and low cost as the internal combustion engine.
   M: These are enormous tasks to accomplish. But scientists are people who are making miracles, aren't they?
   W: Yes, they are. Well, Steven Chu then concluded that achieving all four big breakthroughs would be unlikely. Accordingly, the U.S. Department of Energy dramatically cut funding for hydrogen fuel cells, reducing its support for various programs to nearly a third of previous levels.
   M: That was really bad news for our scientists.
   W: Well, it looked like bad news then. But it was not necessarily a bad thing: Established scientists saw an abrupt decrease in funding opportunities for hydrogen and refocused their research and resources on other technologies. New technologies come along all the time, pushing aside older ones that are no longer bound for the market. For example, in the case of electric automobiles, scientists had made big breakthroughs, and the technology was finally hitting the market. In the process of making electric car batteries, the industry had met the same problems for hydrogen fuel-cells: the production cost, the safe storing method, the charging infrastructure and the improved capacity. But they are being solved one by one.
   M: What do you think of the prospect of new energy vehicles?
   W: I'm very optimistic. If you look at the development of electric cars in this country, Europe and China, you realize that science nowadays advances very quickly, and changes in technology that affect people's everyday lives can occur very fast. I wouldn't be surprised when one day the traditional gasoline-powered automobiles are replaced by new energy vehicles such as solar, electric or hydrogen-powered cars.
   What was the prediction by scientists in the nineteen seventies?