题目内容：
Questionsarebasedonthefollowingpassage. Americansseemtobecoolingtowardglobalwarming.Just57percentthinkthereissol-idevidencetheworldisgettingwarmer,down20pointsinjustthreeyears,anewpollsays.
Andtheshareofpeoplewhobelievepollutioncausedbyhumansiscausingtemperaturestorisehasalsotakenadip,evenastheUSandworldforumsgearupfor(准备)possibleac-tionagainstclimatechange.
Inapollof1,500adultsreleasedbythePewResearchCentreforthePeople&thePress,thenumberofpeoplesayingthereisstrongscientificevidencethattheEarthhasgottenwarmeroverthepastfewdecadesisdownfrom71percentinApriloflastyearandfrom77percentwhenPewstartedaskingthequestionin2006.Thenumberofpeoplewhoseethesituationasaseriousproblemalsohasdeclined.
Thesteepestdrophasoccurredduringthepastyear,asCongressandtheObamaadmin-istrationhavetakenstepstocontrolheat-trappingemissionsforthefirsttimeandinterna-tionalnegotiationsforanewtreatytoslowglobalwarminghavebeenunderway.Atthesametime,therehasbeenmountingscientificevidenceofclimatechange--frommeltingicecapstotheworld'soceanshittingthehighestmonthlyrecordedtemperaturesthissummer.
Thepollwasreleasedadayafter18scientificorganisationswroteCongresstoreaf-firmtheconsensusbehindglobalwarming.AfederalgovernmentreportrecentlyfoundthatglobalwarmingisupsettingtheArctic'sthermostat(恒温器).
Onlyaboutathird,or36percentoftherespondents,feelthathumanactivities--suchaspollutionfrompowerplants,factoriesandautomobiles--arebehindatemperaturein-crease.That'sdownfrom47percentfrom2006throughlastyear'spoll.
"Theprioritythatpeoplegivetopollutionandenvironmentalconcernsandawholehostofotherissuesisdownbecauseoftheeconomyandbecauseofthefocusonotherthings,"suggestedAndrewKohut,thedirectoroftheresearchcenter,whichconductedthepollfromSept.30toOct.4."Whenthefocusisonotherthings,peopleforgetandseetheseissuesaslessgrave,"AndrewWeaversaid,aprofessorofclimateanalysisattheUniversityofVicto-riainBritishColumbia,"andpoliticscouldbedrowningoutscientificawareness."
Thephrase"takenadip"(Line4,Para.1)istheclosestinmeaningto__________. A．plungedintodanger
B．beenenjoyed
C．undergoneadecline
D．beendrowned
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