Questions 11－15  are  based on  the following passage：

    The next decade could see commuters speeding to work at about 300 miles per hour

aboard  magnetic  levitation  vehicles，according  to  a report by  Argoanne  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．Argonme 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

 << 上一页  [21] [22] [23] [24] [25] [26] [27] [28] [29] [30]  ... 下一页  >>