题目内容：
LookingintotheFutureBertrandRussell,afamousphilosopher,saidin1944,“Theonethingthestudyofthepastteachesusisthatthefutureisneverhowpeopleimagineitwillbe.”
In1946,physicistspredictedthatwithintwentyyears,mostoftheworld’senergywouldbesuppliedbynuclearpower.__________（46）In1951,afamoussurgeonsaidthatheandhiscolleagueswereconfidentthat“bytheendofthe1950s,acureformostifnotallcancerswillhavebeenfound.”In1954,anAmericaneconomistpredictedAmericanswouldgoongettingricherandricher.___________（47）.
Intheyear1969,anautomationengineerworkingforMaxFactorCosmeticsinBritainsaidthat“withintwentyortwenty-fiveyearsfactoriesthattodayemployhundredsofworkerswillneedonlyfiveortencomputertechnicianstorunthem.”_____________（48）.
Intheearly1970s,thereweremanypredictionsthatbeforetheendofthecenturymosthomesintheUnitedStates,EuropeandJapanwouldhavecomputersinthem.___________（49）
Longbefore1980,itwaspredictedthatinsteadoflettingnatureandluckchoosetheirchildren’scharacteristics,peoplewouldhavetodecidewhichcharacteristicstheywantedtheirchildrentoinheritfromthemandpreviousgenerationsintheirfamilies.____________（50）Wemaybeabletohave“undesirable”characteristicschangedordestroyedthroughgenetictherapy.PerhapswemayevenbegintowishthatBertrandRussellwasrightwhenhesaidthathistoryteachesusthatthefutureisneverlikethatfutureweimagine.
A．“Bytheendofthec
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