Passage2 Birdsareacriticalpartofourecologicalsystem.Butmorethanever,birdsarethreatenedbyhumanpollutionandclimatechange. Weneedthebirdstoeatinsects,moveseedsandpollenaround,transfernutrientsfromseatoland,cleanupafterthemassdeathoftheannualPacificsalmonruns,orwhenawildanimalfallsanywhereinafieldorforest. HowcouldweenjoyspringwithoutthebirdsflittingbusilyinourgardenordroppingbytocheckouttheflowersinoururbanwindowboxCanyoucontemplateAmericawithoutthesoaringbaldeagle,oreventhosescavengerslikethepigeonsandgullsthatcleanupdiscardedfoodscrapsonourcitystreetsandwaterfrontsHowdiminishedourliveswouldbewithoutthem Scavengingeaglesandcondorsneedhunterstobehaveresponsiblyandbury,orremove,theremainsofanyshotdeerpepperedwithfragmentsofleadbullets.Loons,ducksandotherwaterbirdswillbepoisonedbyleadbulletsandleadfishingsinkersifweallowsuchobjectstodropintheirfeedingspace. Allseaandshorebirds,eventhepuffinsandguillemotsoftheotherwisepristineAleutians,needustomakesurethatnootherheavymetals,likemercuryandcadmium,aredumpedinriversandmaketheirwayacrosstheoceans. Birdsliketheterns,knotsandshearwatersthatmigratebetweenthefarnorthanddeep,deep,southofourplanetneedpeopleeverywheretoceaseanddesistfromfillingintheirwetlandfuelstopsandreststations,andfromconstructinggolfingresortsandfactoriesintheirfeedingandbreedinggrounds. Seabirdsareamongthemostendangeredvertebratespeciesontheplanet,withtheInternationalUnionforConservationofNatureclassifying97speciesasgloballythreatened,and17inthehighestcategoryofcriticallythreatened.Ofgreatestconcernarethepelicansofthesouthernoceansandthespectacular,butslow-breedingalbatross. Plasticbagsmustbeeliminatedfromnaturalenvironmentssoseaandshorebirdsdon′tmistakenlycarrysuchdebrisbacktofeedtheirchicks,withinvariablylethalconsequences.Thealbatross,cormorantsandheronsneedustostopover-fishingandcompromisingtheirnormalfoodsupply. Thepelicans,penguinsandallthebirdsthatinhabit,orvisit,ourcoastlinesneedustoensurethatwedonotdumpoilintogulfsandbays,orreleasesomuchcarbondioxideintotheatmospherethattheoceansturnacidicandwelosethemusselsandoysters,themassofcalcareousplanktonthatfeedssomanycreatures,andthecoralreefsthatnurtureenormousnumbersofediblespecies. Thinkaboutit:Wesharethissmallgreenplanet.Astheyfly,feedandnest,thebirdsmonitorthehealthofthenaturalworldforus,providedthatwe,inturn,maketheefforttoaccessthatkeyinformation. Thebirdsandhumansarebothlarge,complexandultimatelyvulnerableorganismsthatinhabitthetopofthefoodchain.Attheendoftheday,theirfatewillbeourfate. Whichofthefollowingisclosestinmeaningtotheunderlinedword"contemplate"inPARAGRAPHTHREE
A.Live in. B.Think about. C.Arrive at. D.Comment on.正确答案B
