Assuming that a constant travel-time budget, geographic constraints and short-term infrast
We expect that throughout the period 1990~2050, the【46】North American will continue to devote most of his or her 1.1-hour travel-time【47】to automobile travel. The very large demand【48】air travel (or high-speed mil travel) that will be manifest in 2050【49】to only 12 minutes per person a day; a little time goes a long way in the air. In several developing regions, most travel【50】in 2050 will still be devoted to nonmotorized modes. Buses will persist【51】the primary form. of motorized transportation in developing countries for decades.【52】important air travel becomes, buses, automobiles and【53】lowspeed trains will surely go on serving vital functions.【54】of the super-rich already commute and shop in aircraft, but average people will continue to spend most of their travel time on the【55】.
(21)
A.frankly
B.exceptionally
C.unfortunately
D.notably