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 （天线） 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 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 with a map database. Streets， landmarks and points of interest are included. Most systems are basically identical. The differences come in hardware - the way the computer accepts the driver's request for directions and the way it presents the driving instructions. On most systems， a driver enters a desired address， motorway junction or point of interest via a touch screen or disc. But the Lexus screen goes a step further： you can point to any spot on the map screen and get directions to it. BMW's system offers a set of cross hairs （瞄准器上的十字纹） that can be moved across the map （you have several choices of map scale） to pick a point you'd like to get to. Audi's screen can be switched to TV reception. Even the voices that recite the directions can differ， with better systems like BMW's and Lexus's having a wider vocabulary. The instructions are available in French， German， Spanish， Dutch and Italian， as well as English. The driver can also choose parameters for determining the route： fastest， shortest or no freeways （高速公路）， for example. 21. We learn from the passage that navigation computers ________. A） will greatly promote sales of automobiles B） may help solve potential traffic problems C） are likely to be accepted by more drivers D） wills soon be viewed as a symbol of luxury 22. With a navigation computer， a driver will easily find the best route to his destination ________. 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 23. Despite their varied designs， navigation computers used in cars ________. A） are more or less the same price B） provide directions in much the same way C） work on more or less the same principles D） receive instructions from the same satellites 24. The navigation computer functions ________. A） by means of a direction finder and a speed detector B） basically on satellite signals and a map database C） mainly through the reception of turn-by-turn directions D） by using a screen to display satellite signals 25. The navigation systems in cars like Lexus， BMW and Audi are mentioned to show ________. A） the immaturity of the new technology B） the superiority of the global positioning system C） the cause of price fluctuations in car equipment D） the different ways of providing guidance to the driver Passage Two Questions 26 to 30 are based on the following passage：
“The word's environment is surprisingly healthy. Discuss.” If that were an examination topic， most students would tear it apart， offering a long list of complaints： from local smog （烟雾） to global climate change， from the felling （砍伐） of forests to the extinction of species. The list would largely be accurate， the concern legitimate. Yet the students who should be given the highest marks would actually be those who agreed with the statement. The surprise is how good things are， not how bad. After all， the world's population has more than tripled during this century， and world output has risen hugely， so you would expect the earth itself to have been affected. Indeed， if people lived， consumed and produced things in the same way as they did in 1900 （or 1950， or indeed 1980）， the world by now would be a pretty disgusting place： smelly， dirty， toxic and dangerous. But they don't. The reasons why they don't， and why the environment has not been ruined， have to do with prices， technological innovation， social change and government regulation in response to popular pressure. That is why today's environmental problems in the poor countries ought， in principle， to be solvable. Raw materials have not run out， and show no sign of doing so. Logically， one day they must： the planet is a finite place. Yet it is also very big， and man is very ingenious. What has happened is tha
上一页 [1] [2] [3] [4] [5] [6] 下一页