单选题
The next decade could see commuters speeding to work at about 300 miles per hour aboard magnetic levitation vehicles, according to a report by Argonne National Laboratories. But before "maglev" vehicles can become commercial successes, the report says, people need to stop thinking of them as high-speed trains. Instead, consider them low-flying aircraft. Argonne contends that maglev vehicles will be best suited to replace commuter aircraft. Plane flights under 600 miles are the least energy-efficient, and maglev "planes" should cut these fuel needs by up to 75 percent. Reportedly, the money saved by a 2,000- mile maglev network linking major cities world more than pay for its construction in 20 years. The quiet purr of levitating crafts would also be a balm for neighborhoods tormented by the roar of conventional takeoffs and landings. The technology behind magnetic levitation is already well understood, the report notes. The west Germans and the Japanese already well understood, the report notes. The West Germans and the Japanese have several full-scale working models. Meanwhile, research in the United States has lapsed.