reading答案移除大壩珊瑚礁群落動物群居版

DCCBB,ADCAD,BBC,134AADBB,B(C/D)BCB,CDB,135BBDCC,ABACD,DDC,234RemovingFornearlyacentury,twoUnitedStatesernmentalagencies,theUnitedStatesArmyCorpsofEngineersandtheBureauofReclamation,haveconstructeddamstostorewaterandtogenerateelectricity.Buildingthesedamsprovidedcheapelectricity,createdjobsforworkers,stimulatedregionaleconomicdevelopment,andallowedfarmingonlandsthatwouldotherwisebetoodry.Butnoteveryoneagreesthatbigdamprojectsareentirelybeneficial.Theirstoragereservoirsstoptheflowofriversandoftensubmergetowns,farms,andhistoricsites.Theypreventfishmigrationsandchangeaquatichabitatsessentialfornativespecies.Thetidemayhaveturned,infact,againstdambuilding.In1998theArmyCorpsannouncedthatitwouldnolongerbebuildinglargedams.Inthefewremainingsiteswheredamsmightbebuilt,publicoppositionissogreatthatgettingapprovalforprojectsisunlikely.Instead,thenewfocusmaybeonremovingexistingdamsandrestoringnaturalhabitats.In1999BruceBabbitt,thentheUnitedStatesinteriorsecretary,said,“Ofthe75,000largedamsintheUnitedStates,mostwerebuiltalongtimeagoandarenowobsolete,expensive,andunsafe.Theywerebuiltwithnoconsiderationoftheenvironmentalcosts.Asoperatinglicensescomeupforrenewal,damremovalandhabitatrestorationtooriginalstreamflowswillbeamongtheoptionsconsidered.”TheactivehydroelectricdamintheUnitedStatestoberemovedagainstthewishesofitsownerswasthe162-year-oldEdwardsDam,ontheKennebecRiverinAugusta,Maine.Formanyyears,theUnitedStatesFishandWildlifeServicehadadvocatedtheremovalofthisdam,whichpreventedmigrationofsalmon,shad,sturgeon,andotherfishspeciesuptheriver.Inaprecedent-settingdecision,theFederalEnergyRegulatoryCommissionorderedthedamremovedafterconcludingthattheenvironmentalandeconomicbenefitsofafree-flowingriveroutweighedtheelectricitygeneratedbythedam.InJuly1999thedamwasremovedandrestorationworkbeganonwetlandsandstreambankslongThenextdamslikelytobetakendownaretheElwhaandGlinesDamsontheElwhaRiverinOlympicNationalParkinthestateofWashington.BuiltnearlyacenturyagotoprovidepowertolumberandprmillsinthetownofPortAngeles,thesedamsblockedaccesstoupstreamspawningbedsforsixspeciesofsalmononwhatoncewasoneofthemostproductivesalmonriversintheworld.Simplyremovingthedamswillnotrestorethesalmon,however.Where50-kilogramkingsalmononcefoughttheirwayupwaterfallstolaytheireggsingravelbeds,therenowareonlyconcretewallsholdingbackstillwateranddeepbedsofmuddydeposits.Removingthemud,uncoveringgravelbedswherefishspawn,andfindingsuitablesalmontypestorebuildthepopulationisadauntingtask.Congresswillhavetoappropriatesomewherearound$300to$400milliontoremovethesetworelativelysmalldamsandrehabilitatethearea.Environmentalgroups,encouragedbytheseexamples,havebeguntotalkaboutmuoreambitiousprojects.FourgiantdamsontheSnakeRiverinWashingtonState,forexample,mightberemovedtorestoresalmonandsteelheadfishrunstotheheadwatersoftheColumbiaRiver.TheHetchHetchyDaminYosemiteNationalParkmightbetakendowntorevealwhatJohnMuir,thefounderoftheprestigiousenvironmentalanizationSierraClub,calledavalley“justasbeautifulandworthyofpreservationasthemajesticYosemite.”SomegroupshaveevensuggestedremovingtheGlenCanyonDamontheColoradoRiver.Ineachofthesecases,powerfulinterestsstandinopposition.Thesedamsgeneratelow-costelectricityandstorewaterthatisneededforagricultureandindustry.Localeconomies,domesticwaters,andcertaintypesofrecreationallwouldbeseverelyimpactedbydestructionofthesedams.Howdoesoneweighthemanydifferenteconomic,cultural,andaestheticconsiderationsforremovingornotremovingthesedams?Docertaininterests,suchastherightsofnativepeopleorthecontinuedexistenceofnativespeciesoffishorwildlife,takeprecedenceovereconomicfactors,orshouldthisbeautilitariancalculationofthegreatestgoodforthegreatestnumber?Anddoesthatnumberincludeonlyhumansordootherspeciescountaswell?ParagraphFornearlyacentury,twoUnitedStatesernmentalagencies,theUnitedStatesArmyCorpsofEngineersandtheBureauofReclamation,haveconstructeddamstostorewaterandtogenerateelectricity.Buildingthesedamsprovidedcheapelectricity,createdjobsforworkers,stimulatedregionaleconomicdevelopment,andallowedfarmingonlandsthatwouldotherwisebetoodry.Butnoteveryoneagreesthatbigdamprojectsareentirelybeneficial.Theirstoragereservoirsstoptheflowofriversandoftensubmergetowns,farms,andhistoricsites.Theypreventfishmigrationsandchangeaquatichabitatsessentialfornativespecies.Accordingtoparagraph1,buildingdamswasbeneficialineachoffollowingwaysincreasingtheamountoflandthatcouldbeusedforstrengtheninglocalincreasingtheavailabilityoflow- expandingtheaquatichabitatsofnativeParagraphThetidemayhaveturned,infact,againstdambuilding.In1998theArmyCorpsannouncedthatitwouldnolongerbebuildinglargedams.Inthefewremainingsiteswheredamsmightbebuilt,publicoppositionissogreatthatgettingapprovalforprojectsisunlikely.Instead,thenewfocusmaybeonremovingexistingdamsandrestoringnaturalhabitats.In1999BruceBabbitt,thentheUnitedStatesinteriorsecretary,said,“Ofthe75,000largedamsintheUnitedStates,mostwerebuiltalongtimeagoandarenowobsolete,expensive,andunsafe.Theywerebuiltwithnoconsiderationoftheenvironmentalcosts.Asoperatinglicensescomeupforrenewal,damremovalandhabitatrestorationtooriginalstreamflowswillbeamongtheoptionsconsidered.”Accordingtoparagraph2,thelikelihoodthatnewdamswillbebuilthasdecreasedbecauseconstructioncostshaveincreasedsafetystandards emuchpublicoppositiontodamconstructionhasatmostsuitablesitesanexistingdamwouldhavetoberemovedTheword"obsolete"inthepassageisclosestinmeaningoutofParagraph2supportswhichofthefollowingideasaboutoperatinglicensesforlargedams?Since1999licenseshavebeenrenewedonlyforsmallBefore1999,ownersapplyingforalicenserenewalweremorelikelytohavetheirapplicationsthantheywereafterthatdate.Strongpublicoppositiontotheirrenewalwascommonevenbefore1999,butitwasbasedonsafetyconsiderations,notonenvironmentalones.Theenvironmentalcostofdamshasbeenaminorconsiderationinlicenserenewalapplicationssince1999.Paragraph activehydroelectricdamintheUnitedStatestoberemovedagainstthewishesofitsownerswasthe162-year-oldEdwardsDam,ontheKennebecRiverAugusta,Maine.Formanyyears,theUnitedStatesFishandWildlifeServicehadadvocatedtheremovalofthisdam,whichpreventedmigrationofsalmon,shad,sturgeon,andotherfishspeciesuptheriver.Inaprecedent-settingdecision,theFederalEnergyRegulatoryCommissionorderedthedamremovedafterconcludingthattheenvironmentalandeconomicbenefitsofafree-flowingriveroutweighedtheelectricitygeneratedbythedam.InJuly1999thedamwasremovedandrestorationworkbeganonwetlandsandstreambankslongprecedent-setting:開先例Accordingtoparagraph3,whydidtheUnitedStatesFishandWildlifeServicewanttheEdwardsDamremoved?BecauseofthedammadeitBecausethedamwasnegativelyaffectingvariousspeciesofBecausethedamhadcausedwetlandstoBecausethedamnolongerprovidedeconomicParagraph3suggeststhatonemainconsiderationforkeetheEdwardsDamwastheelectricityitthelengthoftimeithadbeeninthehighcostofremovingthefactthatremovingitwouldsetabadParagraphThenextdamslikelytobetakendownaretheElwhaandGlinesDamsontheElwhaRiverinOlympicNationalParkinthestateofWashington.BuiltnearlyacenturyagotoprovidepowertolumberandprmillsinthetownofPortAngeles,thesedamsblockedaccesstoupstreamspawningbedsforsixspeciesofsalmononwhatoncewasoneofthemostproductivesalmonriversintheworld.Simplyremovingthedamswillnotrestorethesalmon,however.Where50-kilogramkingsalmononcefoughttheirwayupwaterfallstolaytheireggsingravelbeds,therenowareonlyconcretewallsholdingbackstillwateranddeepbedsofmuddydeposits.Removingthemud,uncoveringgravelbedswherefishspawn,andfindingsuitablesalmontypestorebuildthepopulationisadauntingtask.Congresswillhavetoappropriatesomewherearound$300to$400milliontoremovethesetworelativelysmalldamsandrehabilitatethearea.Accordingtoparagraph4,whywouldremovingtheElwhaandGlinesdamsnotbeenoughtorestoresalmontotheElwhaRiver?TheyarenottheonlydamsontheElwhaThelumberandp rmillsinPortAngelesalsoblockaccesstoupstreamspawningbeds.ToomanyspeciesofsalmonarecompetingforsurvivalinoneThedamshavelefttheriver’sspawningbedsinanunusableTheword"suitable"inthepassageisclosestinmeaningParagraphEnvironmentalgroups,encouragedbytheseexamples,havebeguntotalkaboutmuoreambitiousprojects.FourgiantdamsontheSnakeRiverinWashingtonState,forexample,mightberemovedtorestoresalmonandsteelheadfishrunstotheheadwatersoftheColumbiaRiver.TheHetchHetchyDaminYosemiteNationalParkmightbetakendowntorevealwhatJohnMuir,thefounderoftheprestigiousenvironmentalanizationSierraClub,calledavalley“justasbeautifulandworthyofpreservationasthemajesticYosemite.”SomegroupshaveevensuggestedremovingtheGlenCanyonDamontheColoradoRiver.Ineachofthesecases,powerfulinterestsstandinopposition.Thesedamsgeneratelow-costelectricityandstorewaterthatisneededforagricultureandindustry.Localeconomies,domesticwaters,andcertaintypesofrecreationallwouldbeseverelyimpactedbydestructionofthesedams.Theword"ambitious"inthepassageisclosestinmeaningimpressivebutdifficulttodangerousandrequireconsiderablecomplexandunlikelytobegreatlyAccordingtoparagraph5,whydoenvironmentalgroupswanttheHetchHetchyDamremoved?TorestoresalmonandsteelheadrunstotheSnakeToallowaccesstotheheadwatersoftheColumbiaToincreasethesizeofYosemiteNationalTorestoreavalleytoitsoriginalParagraphHowdoesoneweighthemanydifferenteconomic,cultural,andaestheticconsiderationsforremovingornotremovingthesedams?Docertaininterests,suchastherightsofnativepeopleorthecontinuedexistenceofnativespeciesoffishorwildlife,takeprecedenceovereconomicfactors,orshouldthisbeautilitariancalculationofthegreatestgoodforthegreatestnumber?Anddoesthatnumberincludeonlyhumansordootherspeciescountaswell?Thephrase"takeprecedenceover"inthepassageisclosestinmeaninghavegreaterimportancegetincludedWhatistheroleofparagraph6intheToproposeamethodfordecidingwhetheragivendamshouldbeToemphasizethecomplexityoftheissuesinvolvedindecidingwhatshouldbedoneaboutdamsTosuggestthattherecenttendencynottobuildnewdamsmaybeTosumupthepointsmadeearlierinthepassageabouttheadvantagesanddisadvantagesofremovingdamsParagraphThenextdamslikelytobetakendownaretheElwhaandGlinesDamsontheElwhaRiverinOlympicNationalParkinthestateofWashington.BuiltnearlyacenturyagotoprovidepowertolumberandprmillsinthetownofPortAngeles,thesedamsblockedaccesstoupstreamspawningbedsforsixspeciesofsalmononwhatoncewasoneofthemostproductivesalmonriversintheworld.Simplyremovingthedamswillnotrestorethesalmon,however.■Where50-kilogramkingsalmononcefoughttheirwayupwaterfallstolaytheireggsingravelbeds,therenowareonlyconcretewallsholdingbackstillwateranddeepbedsofmuddydeposits.■Removingthemud,uncoveringgravelbedswherefishspawn,andfindingsuitablesalmontypestorebuildthepopulationisadauntingtask.■Congresswillhavetoappropriatesomewherearound$300$400milliontoremovethesetworelativelysmalldamsandrehabilitatethe■Lookatthefoursquares[■]thatindicatewherethefollowingsentencecanbeaddedtothepassage.Butasidefromthetechnicalchallenges,theprojectwillalsoposeaseriousfinancialchallenge.WherewouldthesentencebestDirections:Anintroductorysentenceforabriefsummaryofthepassageisprovidedbelow.CompletethesummarybyselectingtheTHREEanswerchoicesthatexpressthemostimportantideasinthepassage.Someanswerchoicesdonotbelonginthesummarybecausetheyexpreeasthatarenotpresentedinthepassageorareminorideasinthepassage.Thisquestionisworth2points.Dragyourchoicestothespaceswheretheybelong.Toreviewthepassage,clickonViewText.ManyManydamswerebuiltintheUnitedStatesduringthelastcentury,andprovidedprovidedabroadrangeofeconomic●●●AnswerUntilrecently,theemphasisindambuildingwasontheeconomicbenefitsoflow-costenergyandwaterthatdamsprovided,butmoreattentionisnowbeingpaidtothedamagetheyEnvironmentalgroupsnowhaveaverygoodchanceofforcingtheremovaloftwomajordams,theGlenCanyonDamontheColoradoandtheHetchHetchyDaminYosemite.（第五段）Theremovalofdamsremainscontroversialbecauseofhighrestorationcosts,lossoflow-costelectricity,andthelossofwaterstoragefacilities.（第六段）

Sincethelate1990s,theernmenthasstoppedbuildinglargedams,insteadfocusingonremovingexistingdamsandrestoringnatural（第二段Untilrecently,themainreasonforremovingdamswastorestoresalmonruns,butitisnowrecognizedthatamoreimportantreasontoremovedamsisthattheyarenolongersafe.AlthoughtheU.S. originallyplannedtoremovetheElwhaandGlinesDamsinWashington,theenormousexpenseofremovalhasresultedinapostponementofthisCoralReefCoralreefsaremassiveunderwaterstructuresmadefromthehardlimestoneexoskeletonsofthousandsoftinylivinganisms(coralpolyps)producedoneontopofanotherinwarm,clear,shallowoceanwaters.Livingpolypsextendupwardandoutwardfromthecoralcolonycenterandliveontopoftheolddeadexoskeletons.Coralreefcommunitiesarecrowdedwithotheranimalsrepresentingvirtuallyeverymajoranimalphylum.Spaceisatapremiumonreefs,corals,seaweeds(variousformsofalgae),sponges,orotheranismscovervirtuallyeverysurface.Becausebothcoralsandalgaerequirelighttosurvive,accesstolight,likespace,isalsoaresourcesubjecttocompetition.Fast-growing,branchingcoralscangrowoverslower-growing,encrusting,ormassivecoralsanddenythemlight.Inresponse,theslower-growingformscanextendstingingfilamentsfromtheirdigestiveandkilltheircompetitor’spolyps.Undamagedpolypsonthefaster-growing,branchingcoral,however,maygrowverylongsweepertentacles,containingpowerfulnematocysts(stingers)thatkillpolypsontheslower-growingform.Thefaster-growingformrepairsthedamageandcontinuestoovergrowitscompetitor.Inadditiontosweepertentaclesandstingingfilaments,coralshaveseveralothermechanismsavailableforattackordefense.Ingeneral,slower-growingcoralsaremoreaggressivethanfast-growingspecies.Incaseswhereacompetitorcannotbe e,however,coralsmaysurvivebytakingadvantageofdifferencesinlocalhabitats.Massivecoralsaregenerallymoreshadetolerantandabletosurviveatgreaterdepths.Therefore,onmanyreefsitisthefast-growing,branchingcoralsthatultimaydominateattheupper,shallowerportionofthereef,whereasmoremassiveformsdominateindeeperCoralsalsomustcompetewithotherreefanisms,eachwithitsownstrategiesforsurvival.Sponges,softcorals,andseaweeds(algae)canovergrowstonycoralsandsmotherthem.Algaearecompetitivelysuperiortocoralsinshallowwaterbutlesssoatdepth.Survivalofcoralinshallowwater,therefore,maydependongrazingbyplant-eatingechinoderms(starfishandseaurchins)andfishes.InJamaica,overfishingremovedmostoftheplant-eatingfishfromcoralreefs.Initially,algalgrowthwaskeptincheckbygrazingseaurchins,butin1982,apathogenreducedthepopulationby99percent.Withoutgrazers,thealgaewereabletocompleyovergrowthecoral.Competitionmayoccuramongotherreefcommunities.Grazingbyurchinsandfishesisimportantinpreventingseaweedsfromovergrowingthereef.Thedominantalgaeonahealthyreefareusuallyfast-growingfilamentousformsorcorallinealgae,wellprotectedbycalcification(hardening)andtheofnoxiouschemicals.Thesealgaeareinferiorcompetitorstolarger,fleshierseaweeds,sograzingbyurchinsandfishesonthelargerseaweedsallowsthesealgaetopersist.Grazingonplantsisgreatestintheshallowreefareasbutdecreaseswithdepth,wherelowertemperaturesandlightreducealgalgrowth.Thereefis,therefore,amosaicofmicrohabitatswithdifferentlevelsofgrazinganddifferentalgalcommunities.Anadditionalcomplexityarisesfromtheactivityofdamselfish.Becausetheyareterritorial,manydamselfishspeciesexcludegrazersandotherspeciesfromcertainareasofthereef.Algaegrowrapidlyintheseterritories,providinghabitatformanysmallinvertebratesbutovergrowingthecorals.Branchingcoralstendtodominateindamselfishterritoriesbecausetheyareuprightandfastergrowingthanthemoremassiveorencrustingforms.Althoughlessstudiedthanonrockyshores,predationalmostcertainlyhasasignificantinfluenceonthecommunitystructureofcoralreefs.Fishandotherpredatorsmaypreferentiallypreyonsuchcompetitorsofcoralsasspongesandgonians,givingcompetitivelyinferiorreefcoralsanadvantageinsecuringspace.Manyspeciesoffish,mollusks,andcrustaceansalsofeeddirectlyoncoralpolyps.Severalsurgeonfishandparrotfishmayactuallypasscoralskeletonsthroughtheirdigestivetractsandaddsedimenttothereef.Bothfishandinvertebratecorallivores(coral-feedinganisms)seemtoattackfaster-growing,branchingspeciespreferentially,perhapspreventingslower-growingformsfrombeingovergrown.Corallivores,however,rarelyevercompleydestroyacoralcolonyexceptincaseswheretropicalstormsorhumanshavealreadydoneseveredamage.Thefactthatalmostallsmallinvertebratesonreefsaresowellhiddenorhighlycamouflagedisanotherindicatorofhowprevalentpredationisonreefsanditsimportanceindeterminingreefstructure.ParagraphCoralreefsaremassiveunderwaterstructuresmadefromthehardlimestoneexoskeletonsofthousandsoftinylivinganisms(coralpolyps)producedoneontopofanotherinwarm,clear,shallowoceanwaters.Livingpolypsextendupwardandoutwardfromthecoralcolonycenterandliveontopoftheolddeadexoskeletons.Coralreefcommunitiesarecrowdedwithotheranimalsrepresentingvirtuallyeverymajoranimalphylum.Spaceisatapremiumonreefs,corals,seaweeds(variousformsofalgae),sponges,orotheranismscovervirtuallyeverysurface.Becausebothcoralsandalgaerequirelighttosurvive,accesstolight,likespace,isalsoaresourcesubjecttocompetition.Atapremium:Ifsomethingisatapremium,itiswantedorneeded,butisdifficulttogetorachieve.緊缺的稀缺的；②Ifyoubuyorsellsomethingatapremium,youbuyorsellitatahigherpricethanusual,forexamplebecauseitisinshortsupply超出平常價，以高價（買進或售出）Accordingtoparagraph1,allofthefollowingaretrueofcoralreefsCoralreefsgrowbiggestinthedeepestwatersofthe anismslivingaroundcoralreefscompeteforlimitedTherearemany anismsincoralreefCoralreefsconsistoftheouterskeletonsofsmall ParagraphFast-growing,branchingcoralscangrowoverslower-growing,encrusting,ormassivecoralsanddenythemlight.Inresponse,theslower-growingformscanextendstingingfilamentsfromtheirdigestiveandkilltheircompetitor’spolyps.Undamagedpolypsonthefaster-growing,branchingcoral,however,maygrowverylongsweepertentacles,containingpowerfulnematocysts(stingers)thatkillpolypsontheslower-growingform.Thefaster-growingformrepairsthedamageandcontinuestoovergrowitscompetitor.Inadditiontosweepertentaclesandstingingfilaments,coralshaveseveralothermechanismsavailableforattackordefense.，Massivecoral：塊狀珊瑚；Encrust：v.用一層硬殼覆蓋；stingingfilaments：刺人的細絲；sweepertentacles：清道夫觸角，清理者觸角，Accordingtoparagraph2,howdofast-growingbranchingcoralsdefendthemselvesfromattacksbyslower-growingcorals?ByproducingstingingsweeperBygrowingontopoftheslower-growingByblockingthelighttotheslower-growingBydestroyingthestingingfilamentoftheslower-growingTheword"mechanisms"inthepassageisclosestinmeaningParagraphIngeneral,slower-growingcoralsaremoreaggressivethanfast-growingspecies.Incaseswhereacompetitorcannotbe e,however,coralsmaysurvivebytakingadvantageofdifferencesinlocalhabitats.Massivecoralsaregenerallymoreshadetolerantandabletosurviveatgreaterdepths.Therefore,onmanyreefsitisthefast-growing,branchingcoralsthatultimaydominateattheupper,shallowerportionofthereef,whereasmoremassiveformsdominateindeeperTheword y"inthepassageisclosestinmeaningParagraphCoralsalsomustcompetewithotherreefanisms,eachwithitsownstrategiesforsurvival.Sponges,softcorals,andseaweeds(algae)canovergrowstonycoralsandsmotherthem.Algaearecompetitivelysuperiortocoralsinshallowwaterbutlesssoatdepth.Survivalofcoralinshallowwater,therefore,maydependongrazingbyplant-eatingechinoderms(starfishandseaurchins)andfishes.InJamaica,overfishingremovedmostoftheplant-eatingfishfromcoralreefs.Initially,algalgrowthwaskeptincheckbygrazingseaurchins,butin1982,apathogenreducedthepopulationby99percent.Withoutgrazers,thealgaewereabletocompleyovergrowthecoral.Overgrow長的過大，過度生長seaurchin：海膽echinodermsThephrase"keptincheck"inthepassageisclosestinmeaningInparagraph4,whydoestheauthordiscusstheeffectsofremovingplant-eatingfishandseaurchinsfromcoralreefs?ToidentifyasituationthatcontributestothedominanceofcoralsinshallowTodemonstratetheimportanceofgrazingonseaweedsforthesurvivalofsomecoralsToprovideevidencethatseaweedsarebettercompetitorsthancoralatToarguethatseaurchinpathogensalsoattackAccordingtoparagraph4,allofthesepairs anismsareincoralsandalgaeandechinodermsandseaurchinsandParagraphCompetitionmayoccuramongotherreefcommunities.Grazingbyurchinsandfishesisimportantinpreventingseaweedsfromovergrowingthereef.Thedominantalgaeonahealthyreefareusuallyfast-growingfilamentousformsorcorallinealgae,wellprotectedbycalcification(hardening)andtheofnoxiouschemicals.Thesealgaeareinferiorcompetitorstolarger,fleshierseaweeds,sograzingbyurchinsandfishesonthelargerseaweedsallowsthesealgaetopersist.Grazingonplantsisgreatestintheshallowreefareasbutdecreaseswithdepth,wherelowertemperaturesandlightreducealgalgrowth.Thereefis,therefore,amosaicofmicrohabitatswithdifferentlevelsofgrazinganddifferentalgalcommunities.Coralline：adj.珊瑚狀構造的calcification：n.Accordingtoparagraph5,fast-growingfilamentousorcorallinealgaeareusuallythedominantalgaeonhealthycoralreefsinpartbecausetheyarenotaffectedbynoxiouschemicalsproducedbyother arelessattractiveasfoodforseaurchinsandfishesthanbiggerseaweedsoccupytheareasofcoralreefsthathavelowertemperaturesandlesscanliveinawidervarietyofmicrohabitatsthantheircompetitorsParagraphAnadditionalcomplexityarisesfromtheactivityofdamselfish.Becausetheyareterritorial,manydamselfishspeciesexcludegrazersandotherspeciesfromcertainareasofthereef.Algaegrowrapidlyintheseterritories,providinghabitatformanysmallinvertebratesbutovergrowingthecorals.Branchingcoralstendtodominateindamselfishterritoriesbecausetheyareuprightandfastergrowingthanthemoremassiveorencrustingforms.Damselfish：少女Accordingtoparagraph6,whichofthefollowingisaneffectoftheactivityofdamselfishonthereefenvironment?EncrustingcoralsdominateindamselfishThedamselfishattractmanyspeciesofAlgaegrowAlgaldiversityisgreaterthaninotherpartsoftheParagraphAlthoughlessstudiedthanonrockyshores,predationalmostcertainlyhasasignificantinfluenceonthecommunitystructureofcoralreefs.Fishandotherpredatorsmaypreferentiallypreyonsuchcompetitorsofcoralsasspongesandgonians,givingcompetitivelyinferiorreefcoralsanadvantageinsecuringspace.Manyspeciesoffish,mollusks,andcrustaceansalsofeeddirectlyoncoralpolyps.Severalsurgeonfishandparrotfishmayactuallypasscoralskeletonsthroughtheirdigestivetractsandaddsedimenttothereef.Bothfishandinvertebratecorallivores(coral-feedinganisms)seemtoattackfaster-growing,branchingspeciespreferentially,perhapspreventingslower-growingformsfrombeingovergrown.Corallivores,however,rarelyevercompleydestroyacoralcolonyexceptincaseswheretropicalstormsorhumanshavealreadydoneseveredamage.Thefactthatalmostallsmallinvertebratesonreefsaresowellhiddenorhighlycamouflagedisanotherindicatorofhowprevalentpredationonreefsanditsimportanceindeterminingreefstructure. mollusks軟體動物Theword"securing"inthepassageisclosestinmeaninglookingsecure(經過努力)Ifyousecuresomethingthatyouwantorneed,youobtainit,oftenafteralotofeffortWhichofthesentencesbelowbestexpressestheessentialinformationinthehighlightedsentenceinthepassage?Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessentialinformation.ThepresenceofonlyverysmallinvertebratesonareefisanindicationofMostreefsarestructuredinawaywhichallowssmallinvertebratestoremainhiddenorcamouflaged.Almostallsmallinvertebratesarehiddenorcamouflaged,indicatingtheextentandimportanceofpredationtoreefstructure.Almostallofthesmallinvertebratesonreefsaredifficulttofindbecausetheyaresohighlycamouflaged.Paragraph7mentionsallofthefollowingaseffectsofpredationonthecommunitystructureofcoralreefsEXCEPT: CoralsareadvantagedwhenpredatorsprefertoattackcompetitorsofFaster-growingcoralsarepreventedfromovergrowingslower-growingcoralswhenfaster-growingspeciesarepreferredbycompetitors.PredationcontributestothesedimentdepositoftheSmallinvertebratesareexposedtocompetitively ParagraphIngeneral,slower-growingcoralsaremoreaggressivethanfast-growingIncaseswhereacompetitorcannotbe e,however,coralsmaysurvivebytakingadvantageofdifferencesinlocalhabitats.■Massivecoralsaregenerallymoreshadetolerantandabletosurviveatgreaterdepths.■Therefore,onmanyreefsitisthefast-growing,branchingcoralsthatultimaydominateattheupper,shallowerportionofthereef,whereasmoremassivefo