Imaginethesituation．Youaredrivingalongadesertoronamountain．Youhavenoideawhereyouare．Youpassedthelasthousetwohoursago．Thenyourcarbreaksdown．（68）___Youhavenomobilephone．Whatshouldyoudo？Well，nexttimetakeaGPSwithyou．Thisinventionmaybeabletohelpyou．（69）___Itcanfindyourpositiontowithin20metres．AGPScannotstartyourcar，butatleastyouwillknowwhereyouare．
GPS，whichmeansGlobalPositioningSystem，isasmallradioreceiver．Itlookslikeamobilephone．（70）___WealsofindGPSdevicesincars，planes，orboats．Someofthesedeviceshaveelectronicmaps，soyouknowwhereyouare．（71）___
SomepeoplethinkthatinthefuturetheGPSwillbeascommonasthemobile．（72）___herearealsonewusesfortheGPS．Perhapstheywillbecomelikewatches．Everyonewillhaveoneandyouwillneverbelostagain．
从方框中所给的选项中选出能填入空白处的最佳选项，补全短文．其中有一项为多余选项．（10分）
A：Itisadevice（装置） whichusessatellitestofindtheuser'sposition．B：Forexample，inacitytheycantellyouthenameofthestreet．
C：Itisnightanditiscold．
D：TherearethreepartstotheGlobalPositioningSystem．
E：Youcanholditinyourhand，orputinyourpocket．
F：Theyarebecomingcheaperandmoreandmoreaccurate（精确的）．
