托福TPO24综合写作阅读原文+听力原文+满分范文.pdf

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托福TPO24综合写作阅读原文文本：

Animalfossilsusuallyprovideverylittleopportunitytostudytheactualanimal
tissues,becauseinfossilstheanimals'livingtissueshavebeenlargelyreplaced
byminerals.Thus,scientistswereveryexcitedrecentlywhenitappearedthata70-
million-year-oldfossilofTyrannosaurusrex(T.rex),adinosaur,mightstill
containremainsoftheactualtissuesoftheanimal.Thediscoverywasmadewhen
researchersdeliberatelybrokeopentheT.rex’slegbone,therebyexposingits
insidestorevealmaterialsthatseemtoberemainsofbloodvessels,redbloodcells,
andcollagenmatrix.First,thebreakingofthefossilizedlegbonerevealedmany
smallbranchingchannelsinside,whichprobablycorrespondtohollowsinthebones
wherebloodvesselswereoncelocated.Theexcitingfindingwasthepresenceofa
soft,flexibleorganicsubstanceinsidethechannels.Thissoftsubstancemayvery
wellrepresenttheremainsoftheactualbloodvesselsofT.rex.Second,microscopic
examinationofthevariouspartsoftheinnerbonerevealedthepresenceofspheres
thatcouldbetheremainsofredbloodcells.Testsshowedthatthespherescontained
iron-amaterialvitaltotheroleofredbloodcellsintransportingoxygentotissues.
Moreover,thesphereshaddarkredcenters(substanceswithirontendtobereddish
incolor)andwerealsoaboutthesizeofredbloodcells.Third,scientistsperformed
atestonthedinosaurlegbonethatshowedthatitcontainedcollagen.Collagenis
afibrousproteinthatisamaincomponentoflivingbonetissue,inwhichitforms
aso-calledcollagenmatrix.Collagen(oritschemicalderivatives)isexactlythe
kindofbiochemicalmaterialthatonewouldexpecttofindinassociationwithbone
tissue.

托福TPO24综合写作听力原文文本：

Asmuchaswewouldliketohavetheremainsofactualdinosaurtissue,there
aresoundreasonsforbeingskepticaloftheidentificationsmadeinthe
reading.First,thesoft,flexiblesubstanceinsidethebonechannelsisn't
necessarilytheremainsofbloodvessels.Itismuchmorelikelytobesomethingelse.
Likewhat?Youmightsay.Well,longafteranorganismisdied,bacteriasometimes
colonizehollows,emptyareasinbones,likethechannelsthatonceheldblo