题目内容：
根据以下材料，回答题
ToadsAreArthritisandinPain
Arthritisisanillnessthatcancausepainandswellinginyourbones.Toads,abigprobleminthenorthofAustralia,aresufferingfi:ompainfularthritisintheirlegsandbackbone,anewstudyhasshown.
Thetoadsthatjumpthefastestaremorelikelytobelargerandtohavelongerlegs.（46）Thelargeyellowtoads,nativetoSouthandCentralAmerica,wereintroducedintothenoah-easternAustralianstateofQueenslandin1935inanattempttostopbeetlesandotherinsectsfromdestroyingsugarcanecrops.Nowupto200millionofthepoisonoustoadsexistinthecountry,andtheyarerapidlyspreadingthroughthestateofNorthernTerritoryatarateofupto60kmayear.
Thetoadscannowbefoundacrossmorethanonemillionsquarekilometers.（47）AVenezuelanpoisonviruswastriedinthe1990sbuthadtobeabandonedafteritwasfoundtoalsokillnativefrogspecies.
ThetoadshaveseverelyaffectedecosystemsinAustralia.Animals,andsometimespets,thateatthetoadsdieimmediatelyfromtheirpoison,andthetoadsthemselveseatanythingtheycanfitinsidetheirmouth.（48）
Aco-authorofthenewstudy,RickShine,aprofessorattheUniversityofSydney,saysthatlittleattentionhasbeengiventotheproblemsthattoadsface.Rickandhiscolleaguesstudiednearly（50）0toadsfromQueenslandandtheNorthernTerritoryandfoundthatthoseinthelatterstatewereverydifferent.Theywereactive,sprintingdownroadsandbreedingquickly.
Accordingtotheresultsofthestudy,thefastesttoadstravelnearlyonekilometeranight.（49）Butspeedandstrengthcomeataprice--arthritisofthelegsandbackboneduetoconstantpressureplacedonthem.
Inlaboratorytests,theresearchersfoundthatafterabout15minutesofhopping,arthritictoadswouldtravellessdistancewitheachhop(跳跃).（50）Thesetoadsaresoprogrammedtomove,apparently,thatevenwheninpainthetoadstravelledasfastandasfarasthehealthyones,continuingtheirrelentlessmarchacrossthelandscape.
回答(46)题 A．Butthisadvantagealsohasabigdrawback--upto10%ofthebiggesttoadssufferfromarthritis.
B．Thetasknowfacingthecountryishowtoremovethetoads.
C．Butarthritisdidn'tslowdowntoadsoutsidethelaboratory.
D．Toadswithlongerlegsmovefasterandtravellongerdistanceswhiletheothersarebeingleftbehind.
E．Toadsarenotbuilttoberoadrunners--theyarebuilttositaroundpondsandwetareas.
F．Furthermore,theysoontakeoverthenaturalhabitatsofAustralia'snativespecies.
参考答案：
答案解析：