单选题
Assuming that a constant travel-time budget, geographic constraints and short-term infrastructure constraints persist as fundamental features of global mobility, what long-term results can one expect? In high-income regions, 【C1】______North America, our picture suggests that the share of traffic【C2】______supplied by buses and automobiles will decline as high-speed transport rises sharply. In developing countries, we【C3】______the strongest increase to be in the shares first for buses and later for automobiles. Globally, these【C4】______in bus and automobile transport are partially offsetting. In all regions, the share of low-speed mil transport will probably continue its strongly【C5】______decline. We expect that throughout the period 1990—2050, the【C6】______North American will continue to devote most of his or her 1. 1-hour travel-time【C7】______to automobile travel. The very large demand【C8】______air travel(or high-speed mil travel)that will be manifest in 2050【C9】______to only 12 minutes per person a day; a little time goes a long way in the air. In several developing regions, most travel【C10】______in 2050 will still be devoted to nonmotorized modes. Buses will persist【C11】______the primary form of motorized transportation in developing countries for decades.【C12】______important air travel becomes, buses, automobiles and【C13】______low-speed trains will surely go on serving vital functions.【C14】______of the super-rich already commute and shop in aircraft, but average people will continue to spend most of their travel time on the【C15】______.