根据下列文章，回答31～35题。
Intheearly1960sWiltChamberlainwasoneofonlythreeplayersintheNationalBasketballAssociation（NBA）listedatoversevenfeet.Ifhehadplayedlastseason,however,hewouldhavebeenoneof42.Thebodiesplayingmajorprofessionalsportshavechangeddramaticallyovertheyears,andmanagershavebeenmorethanwillingtoadjustteamuniformstofitthegrowingnumbersofbigger,longerframes.
Thetr endinsports,though,maybeobscuringanunrecognizedreality:Americanshavegenerallystoppedgrowing.Thoughtypicallyabouttwoinchestallernowthan140yearsago,today''speople-especiallythoseborntofamilieswhohavelivedintheU.S.formanygenerations-apparentlyreachedtheirlimitintheearly1960s.Andtheyaren’tlikelytogetanytaller.Inthegeneralpopulationtoday,atthisgenetic,environmentallevel,we''veprettymuchgoneasfaraswecango,saysanthropologistWilliamCameronChumleaofWrightStateUniversity.InthecaseofNBAplayers,theirincreaseinheightappearstoresultfromtheincreasinglycommonpracticeofrecruitingplayersfromallovertheworld.
Growth,whichrarelycontinuesbeyondtheageof20,demandscaloriesandnutr ients–notably,protein–tofeedexpandingtissues.Atthestartofthe20thcentury,under-nutr itionandchildhoodinfectionsgotintheway.Butasdietandhealthimproved,childrenandadolescentshave,onaverage,increasedinheightbyaboutaninchandahalfevery20years,apatternknownastheseculartr endinheight.YetaccordingtotheCentersforDiseaseContr olandPrevention,averageheight-5′9〞formen,5′4〞forwomen-hasn''tr eallychangedsince1960.
Geneticallyspeaking,thereareadvantagestoavoidingsubstantialheight.Duringchildbirth,largerbabieshavemoredifficultypassingthroughthebirthcanal.Moreover,eventhoughhumanshavebeenuprightformillionsofyears,ourfeetandbackcontinuetostr ugglewithbipedalpostureandcannoteasilywithstandrepeatedstr ainimposedbyoversizelimbs.Therearesomerealconstr aintsthataresetbythegeneticarchitectureoftheindividualorganism,saysanthropologistWilliamLeonardofNorthwesternUniversity.
Geneticmaximumscanchange,butd on''texpectthistohappensoon.ClaireC．Gordon,senioranthropologistattheArmyResearchCenterinNatick,Mass,ensuresthat90percentoftheuniformsandworkstationsfitr ecruitswithoutalteration.Shesaysthat,unlikethoseforbasketball,thelengthofmilitaryuniformshasnotchangedforsometime.Andifyouneedtopredicthumanheightinthenearfuturetodesignapieceofequipment,Gordonsaysthatbyandlarge,youcouldusetoday’sdataandfeelfairlyconfident.
第31题WiltChamberlainiscitedasanexampleto
A．illustr atethechangeofheightofNBAplayers.
B．showthepopularityofNBAplayersintheU.S……
C．comparedifferentgenerationsofNBAplayers.
D．assesstheachievementsoffamousNBAplayers.
正确答案：AA
文中“…listedatoversevenfeet.Ifhehad….Thebodies..changeddramaticallyovertheyears”可以看出此段主要讲述NBA球员身高的变化;另外，从文章中心来看，可以排出B，C，D。因此选A。
