Computers in Cars

You're far from homeon a lonely road.Shadowy forests stretch away on both sides.A thick mist（雾）makes it difficult to see far beyondyour car's windshield（挡风玻

璃）.

“Can this beroute 90A?”you wonder. if it is,you should be near a town.Yet there's no hintof one .Night is closing in.And you're low on gasoline.

This is a situationwhere an in-car computer that can navigate would be a big help.

A car computer thatnavigates?Yes!Such computers exist.Several experimental models are being testedby General Motors,Ford,Chrysler,and several foreign car

makers.Thesecomputers vary in detail .But they all contain series of maps on videodiscs orvideotapes.For example,one computer system contains 13,300 maps covering the

continental US.

Before starting outon a trip,a driver can type in the code for the region he or she plans to drivethrough .The computer then shows a map of that region.At the same time,a

tiny radio re-ceiverlinked to the computer goes to work.It picks up signals from navigationsatellites such as the NAVSTAR network.Using these signals,the computer shows

the car's positionat all times and displays this position on the map.The computer can alsocalculate and display the best route to follow.

A navigationcomputer may also receive and use data about road construction,weather condi-tions,and traffic jams.This information would be displayed to the driver andthe

computer would alsouse the information to work out alternate（交替的）routes.

Most cars nowadaysalso contain computers that help cars run more efficiently .Microproces- sors（微处理机）control certain engine functionsby regulating the mixing of

fuel. Data on carspeed,oil pressure,revolutions per minute,engine temperature,and fuel level canbe displayed as digital data(numbers)or warning lights.

Some auto designerssuggest that a central computer display be used to clearly present such timelyinformation as car speed and fuel level.Warning lights would indicate a

drop in oil pres-sure or a sudden rise in engine temperature .To get more information on theseconditions,the driver could call it up on the computer display screen.When

needed,the computercould be “asked”to provide navigation aid or information about the car'scondition.

Without signalsfrom navigation satellites,the in-car computer______.

A.would still beable to locate the car's position at all times

B. would fail tolocate the car's position

C. could still workout the best route to follow

D. would seek helpfrom the radio receiver linked to it