[单项选择] Navigation computers, now sold by most car makers, cost $ 2000 and up. No surprise, then, that they are most often found in luxury cars, like Lexus, BMW and Audi. But it is a developing technology-meaning prices should eventually drop-and the market does seem to be growing. Even at current prices, a navigation computer is impressive, It can guide you from point to point in most major cities with precise turn by-turn directions spoken by a clear human sounding voice, and written on a screen in front of the driver. The computer works with an antenna that takes signals from no fewer than three of the 24 Global Positioning System (GPS) satellites. By measuring the time required for a signal to travel between the satellites and the antenna, the car’’s location can be pinned down within 100 meters. The satellite signals, along with inputs on speed from a wheel speed sensor and direction from a meter, determine the car’’s position even as it moves. This information is combined
A. by inputting the exact address
B. by indicating the location of his car
C. by checking his computer database
D. by giving vocal orders to the computer

[单项选择]Navigation computers, now sold by most car-makers, cost $2,000 and up. No surprise, then, that they are most often found in luxury cars, like Lexus, BMW and Audi. But it is a developing technology—meaning prices should eventually drop—and the market does seem to be growing.
Even at current prices, a navigation computer is impressive. It can guide you from point to point in most major cities with precise turn-by-turn directions—spoken by a clear human-sounding voice, and written on a screen in front of the driver.
The computer works with an antenna (无线) that takes signals from no fewer than three of the 24 global positioning system (GPS) satellites. By measuring the time required for a signal to travel between the satellites and the antenna, the car’s location can he pinned down within 100 meters.
The satellite signals, along with inputs on speed from a wheel-speed sensor and direction from a meter, determine the car’s position even as it moves. This information is
A. will greatly promote sales of automobiles
B. may help solve potential traffic problems
C. are likely to be accepted by more drivers
D. will soon be viewed as a symbol of luxury