比如 oG中的这个题。 The difficulty with the proposed high-speed train line is that a used plane can be bought for one-third the price of the train line, and the plane, which is just as fast, can fly anywhere. The train would be a fixed linear system, and we live in a world that is spreading out in all directions and in which consumers choose the freewheel systems (cars, buses, aircraft), which do not have fixed routes. Thus a sufficient market for the train will not exist.
Which of the following, if true, most severely weakens the argument presented above?
(A) Cars, buses, and planes require the efforts of drivers and pilots to guide them, whereas the train will be guided mechanically. (B) Cars and buses are not nearly as fast as the high-speed train will be. (C) Planes are not a free-wheel system because they can fly only between airports, which are less convenient for consumers than the highspeed train’s stations would be. (D) The high-speed train line cannot use currently underutilized train stations in large cities.C (E) For long trips, most people prefer to fly rather than to take ground-level transportation.
Situation A free-wheel system of transportation, the airplane, is as fast as a fixed linear system, the high-speed train. Because people prefer free-wheel systems that do not have fixed routes, the high-speed train will never find a sufficient market.
Reasoning What is the potential weakness in this argument? The passage argues that consumers will choose to fly rather than use the high-speed train. The argument is based upon a consumer preference for free-wheel systems over fixed linear systems. The definition of a free-wheel system is one that does not have fixed routes. The argument is weakened by any challenge to the definition of flying as a free-wheel transportation system. It is true that airplanes may be able to go almost anywhere, but commercial airlines do establish fixed routes and necessarily must travel to and from airports. Furthermore, if airports are less conveniently located for consumers than are train terminals, consumers might well prefer the more convenient of the two fixed-route alternatives.
A The method of guidance is irrelevant to the argument about free-wheel versus fixed linear systems.
B The passage compares the speed and system models of airplanes and high-speed trains. The argument does not incorporate buses and cars, which are included only to give examples of freewheel systems, and so this statement is irrelevant.
C Correct. This statement properly identifies the weakness in the argument: Airplanes are not truly a free-wheel system because they are restricted to traveling between airports. Additionally, airports tend to be less conveniently located than train terminals, which has further potential to weaken the argument in favor of airplanes.
D The inability of high-speed trains to use some convenient train stations strengthens, rather than weakens, the argument in favor of airplanes.
E Consumer preference for air travel over ground travel on long trips strengthens, rather than weakens, the argument in favor of airplanes.