【正确答案】
D
【答案解析】[听力原文] Every year, people in America use energy equal to over 30 million barrels of oil each day. That's energy in all forms: oil, gas, coal, nuclear, solar and even wind power. Viewed from a scientist's standpoint, all of the energy contained in fuel, either now or in the future, becomes heat. Some of the heat is used directly or produces useful work. The rest is lost or rejected, radiated into the atmosphere from the engines, motors, boilers and all the other energy-consuming machinery that makes America's wheels go around. If we could figure out how to improve the efficiency with which we use energy, we could do a lot more work with the energy that is available. With money and careful planning, we can boost efficiency up to a point. Yet improvement won't come easily. It won't come overnight and there are limits beyond which not even science can take us. According to the Centre for Strategic and International Studies, about three quarters of the energy we use to move things, including ourselves, accomplishes no useful work. In terms of efficiency and cleanness, buses, trains and other forms of public or mass transportation are superior to the private automobile, but only if they operate at near capacity. Otherwise, their overall efficiency is poor. For some people, mass transit may answer all transportation needs. For others, a combination of mass transit and private transportation may be desirable. Better design and wiser use of both mass transit systems and private vehicles will play an important part in helping America get more out of energy used for transportation. What does the speaker say about energy used in the United States? 短文第一句就提到美国人使用的能源相当于每天消耗3000多万桶石油，因此可以得出D项为正确答案。其他三项均与原文内容不符，故排除。