PassageOne
Questions 46 to 50 arebasedonthefollowingpassage.
Californiahasbeenfacingadroughtformanyyearsnow, withcertainareasevenhavingtopumpfreshwaterhundredsofmilestotheirdistributionsystem. Theproblemisgrowingasthepopulationofthestatecontinuestoexpand. Newresearchhasfounddeepwaterreservesunderthestatewhichcouldhelpsolvetheirdroughtcrisis. Previousdrillingofwellscouldonlyreachdepthsof 1,000 feet, butduetonewpumpingpractices, waterdeeperthanthiscannowbeextracted （抽取）. TheteamatStanfordinvestigatedtheaquifers（地下蓄水层）belowthisdepthandfoundthatreservesmaybetriplewhatwaspreviouslythought.
Itisprofitabletodrilltodepthsmorethan 1,000 feetforoilandgasextraction, butonlyrecentlyinCaliforniahasitbecomeprofitabletopumpwaterfromthisdepth. Theaquifersrangefrom 1,000 to3,000 feetbelowtheground, whichmeansthatpumpingwillbeexpensiveandthereareotherconcerns. Thebiggestconcernofpumpingoutwaterfromthisdeepisthegradualsettingdownofthelandsurface. Asthewaterispumpedout, thevacantspaceleftiscompactedbytheweightoftheearthabove.
Eventhoughpumpingfromthesedepthsisexpensive, itisstillcheaperthandesalinating（脱盐）theoceanwaterinthelargelycoastalstate. Somedesalinationplantsexistwherefeasible, buttheyarecostlytorunandcanneedconstantrepairs. Wellsaremuchmorereliablesourcesoffreshwater, andCaliforniaishopingthatthesedeepwellsmaybetheanswertotheirseverewatershortage.
Oneproblemwiththesesourcesisthatthedeepwateralsohasahigherlevelofsaltthanshalloweraquifers. Thismeansthatsomewellsmayevenneedtoundergodesalinationafterextraction, thusincreasingthecost. Researchfromtheexhaustivestudyofgroundwaterfromover 950 drillinglogshasjustbeenpublished. Newestimatesofthewaterreservesnowgoupto 2,700 billioncubicmetersoffreshwater.
46. HowcouldCalifornia'sdroughtcrisisbesolvedaccordingtosomeresearchers?
A) Bybuildingmorereservesofgroundwater.
B) Bydrawingwaterfromthedepthsoftheearth.
C) Bydevelopingmoreadvanceddrillingdevices.
D) Byupgradingitswaterdistributionsystem.
47. Whatcanbeinferredaboutextractingwaterfromdeepaquifers?
A) Itwasdeemedvitaltosolvingthewaterproblem.
B) Itwasnotconsideredworththeexpense.
C) Itmaynotprovidequalityfreshwater.
D) Itisboundtogainsupportfromthelocalpeople.
48. Whatismentionedasaconsequenceofextractingwaterfromdeepunderground?
A) Thesinkingoflandsurface.
B) Theharmtotheecosystem.
C) Thedamagetoaquifers.
D) Thechangeoftheclimate.
49. Whatdoestheauthorsayaboutdeepwells?
A) Theyrunwithoutanyneedforrepairs.
B) Theyareentirelyfreefrompollutants.
C) Theyaretheultimatesolutiontodroughts.
D) Theyprovideasteadysupplyoffreshwater.
50. Whatmayhappenwhendeepaquifersareusedaswatersources?
A) People'shealthmayimprovewithcleanerwater.
B) People'swaterbillsmaybeloweredconsiderably.
C) Thecostmaygoupduetodesalination.
D) Theymaybeexhaustedsoonerorlater.