Passage4
Questions16to20arebasedonthefollowingpassage:
Thenewglobalsatellitecommunicationssystemswillofferthreekindsservice,whichmayoverlapinmanydifferentkindsofreceivers.
VOICE.SatellitetelephoneswillbeabletomakecallsfromanywhereontheEarthtoanywhereelse.Thatcouldmakethemespeciallyusefultoremote,thirdworldvillages(someofwhichalreadyusestationarysatellitetelephones),explorersanddisaster-reliefteams.Today’smobiletelephonesdependonearth-boundtransmitters,wheretechnicalstandardsvaryfromcountrytocountry.Sobusinesstravelerscannotusetheirmobilephonesoninternationaltrips.Satellitetelephoneswouldmakethatpossible.
MESSAGING.Satellitemassagershavethesameglobalcoverageassatellitetelephones,butcarrytextalone,whichcouldbeusefulforthosewithlaptopcomputers.Equippedwithasmallscreenliketoday’spapers,satellitemassagerswillalsoreceiveshortmessages.
TRACKING.Voiceandmessagingsystemswillalsotelltheiruserswheretheyaretowithinafewhundredmeters.Combinedwiththemessagingservice,thelocationservicecouldhelprescueteamstofindstrandedadventurers,thepolicetofindstolencars,exporterstofollowtheprogressofcargoes,andhaulagecompaniestocheckthatdriversarenotdetouringthepub.America’smilitaryGlobalPositioningSystem(GPS)satellitewillprovidebetterpositioninginformationtoanyonewhohasareceiverfortheirsignals,butGPSdoesnotcarrymessages,sosuchareceivercannotbeusedonitsownfortrackingorrescue.Bythemid-1990s,GPSreceiverswillbeabletotellpeoplewheretheyaretowithin70metersanywhereintheworld,andtowithinameterorsoinareaswheretheserviceissupplementedbyground-basedtransmitter.
16.Globalsatellitecommunicationssystemswillbeusefulto.
A.laptopcomputerusers
B.remotevillages
C.disaster-reliefteams
D.allabove
17.Satellitetelephonewillmake.
A.businesstravelersusemobilephonesoninternationaltrips
B.possiblecallsfromanywhereonearthtoanywhereelse
C.explorershappy
D.allabove
18.Whichofthefollowingistrue?
A.ThepositioningprecisionofthevoicesystemisbetterthanthatofGPS.
B.ThepositioningprecisionofGPSisBetterthanthatofthevoicesystem.
C.ThepositioningprecisionofthemessagingsystemisbetterthanofGPS.
D.Thepositioningprecisionofvoicesystemisbetterthanthatofthemessagingsystem.
19.Whatcanwesayaboutthenewglobalsatellitecommunicationssystems?
A.Theyarewidelyused.
B.Theyareveryhelpful.
C.Theyarecostly.
D.BothAandB.
20.Whichofthefollowingmaybethebesttitleforthepassage?
A.GlobalSatelliteCommunications
B.NewVoiceandMessagingSystem
C.NewGenerationSatellite
D.AlwaysinTouch
接生过程中，下列哪项是错误的