2018年11月24日托福聽力考試機(jī)經(jīng)

1、2018年11月24日托福聽力考試機(jī)經(jīng)本文從網(wǎng)絡(luò)收集而來，上傳到平臺為了幫到更多的人，如果您需要使用本文檔，請點(diǎn)擊下載按鈕下載本文檔（有償下載），另外祝您生活愉快，工作順利，萬事如意！關(guān)于2019年11月24日的托福聽力考試，想必大家都非常感興趣，那么今天就跟著出國留學(xué)網(wǎng)來看看2019年11月24日托福聽力考試機(jī)經(jīng)。題目isthelecturemainlyabouthypothesesaboutdinosaursresultingfromtissueanalysisorsthatallowdinosaurbonestobewellpreservedroleofhistologyindeterm

2、iningnutritionalneedsofdinosaursidentificationofsomerecentlydiscovereddinosaurbones2. hydoestheprofessordescribetheprocessofpetrifaction?clarifythedifferencebetweenboneandsofttissueexplainwhyhistologycanbeusedondinosaurbonesremindstudentsofhowlongagodinosaursliveddescribetheoriginsofsomecracksindino

3、saurbones3. hatwouldresearchershaveconcludediftheyhad本文為網(wǎng)絡(luò)收集精選范文、公文、論文、和其他應(yīng)用文檔，如需本文，請下載foundstress-fracturesintheskullsofcertaindinosaurstheyhadbeenundernourishedtheyhadengagedinheadbuttingbehaviortheskullboneswerenotwellpreservedtheskullboneswerefragile4. Accordingtotheprofessor,whatevidencesupport

4、edtheoriginalhypothesisthatApatosaurustookdecadestoreachitsadultsizeClickon2answers.tboneshadmanygrowthrings.B. Itsenvironmentdidnotsupportmanyplants.C. Itwasaverylargeanimal.rndayreptilesgrowslowly.5. riortotheuseofhistologicalanalysis,whatwouldresearchershaveprobablyconcludeduponthediscoveryoftheb

5、onesofasmallsauropodbonesbelongedtoanewspeciesofsauropod.bonesbelongedtoadwarfspeciesofdinosaur.dinosaurshabitathadlimitedresources.bonesbelongedtoanimmaturedinosaur.doestheprofessorsaythissuggestareasonthatthedinosaurdidnotsurvivefindoutifthestudentsbelievesuchrapidgrowthwaspossibleexpresshersenseo

6、famazementshowhowinaccurateresearcherswereintheiroriginalprediction聽力文本Narrator:Listentopartofalectureinabiologyclass.ProfessorWehaveverygoodideasaboutthevariousshapesandsizesofdinosaursfromstudyingtheirpetrifiedbones.Butwe'vehadtohypothesizeaboutthingsliketheirbehaviorsandlifespanbecausemuchoft

7、hatkindofinformationisn'tpreservedthewaybonesandteethareorsowethought.Now,justtoreviewasecondthedinosaurboneswestudiedwerepreservedandturnedtostonemillionsofyearsagothroughtheprocessofpetrifaction.Petrifactioniswhenalloftheoriginalbiologicalmaterialgetsreplacedwithmineralswithoutlosingitsorigina

8、lshapeordetails.Somepetrifieddinosaurbonescontainalmostperfectlypreservedmicrostructuresassmallasindividualcells.Andwhenbonesarethatwellpreserved,wecanusehistologytoexaminethem.Histologyisthestudyofbiologicaltissue.Andinthiscase,histologyisbeingusedtostudypetrifiedbonetissue.Todothat,thepetrifiedbon

9、ehastobecutintoslicessothinthatlightcanpassthroughthem.Thenyoucanexaminethemunderamicroscope.Itturnsthatthepreservedmicrostructurescontainsalotofinformation,includingcluestobehavior.Infact,long-standinghypothesesaboutdinosaurbehaviorarebeingprovedwrongandnewhypothesesaboutdinosaurbehavioraretakingth

10、eirplace.Forexample,there'sonedinosaurthatweknowhadahighdome-shapedskullcomposedofthickbone.Sincethe1950s,wethoughtthatwithsuchathickskullthatmalesprobablybuttedheadsjustlikebig-hornsheepdotoday,probablywhencompetingformates.Butjustacoupleofyearsago,someuniversityresearchersintheUnitedStatestook

11、acloselookatthehistologicalfindingsinseveraloftheseskullstolookforevidenceofheadbuttinglikehealedcracksorstressfractures.Buttheanalysisclearlyshowedthattherewasnosignofthatkindofstresstothebones.Instead,whattheyfoundwassmallstructuresthatlookliketheymayhaveactuallyanchoredacresttotheskull.Female:Pro

12、fessorAcrest,maybelikearoostercomt?Sonowpaleontologistsarewonderingwhatthecrestmighthavebeenusedfor.Display?Recognition?Butcertainlynotforheadbutting.Now,anotherlong-standinghypothesiswasthatthereallybigdinosaurstookdecadestoreachfullsize.Afterall,theyhatchedsomefairlysmalleggsandtheyhadalotofgrowin

13、gtodosoit'safairlylogicalassumptionthatittookalongtimetoreachtheirgiantsizes.ThenresearchersdidahistologicalexaminationofApatosaurusbones.Apatosauruswasaspeciesofsauropod,agiantplant-eatingdinosaur.Ithadalongneckandalongtailanditsfullsizewasabout25meterslongandweighedabout25tons.Nowtheideathatth

14、eApatosaurusgrewslowlywasbasedonmanyobservationsincludingitsenormoussizeandthefactthatlargemodernreptilesgrowslowly.Forexample,Apatosaurushasarelativelysmallmouthandsimplefeetandtheplantsthatlivedatthattimewerenotparticularlynutritious.Altogether,it'snotarecipeforfastgrowth.However,underamicrosc

15、opeit'sclearthatdinosaurboneshavegrowthringsandbycountingthemliketreerings,paleontologistscaninferhowmanyyearsofboneshavegrown.Andwhencomparingthegrowthringsfromseveralspecimensofthesamespeciesofdinosaur,paleontologistscanfigureoutgrowthrateforthatspecies.Wellsurprisingly,thatgiantApatosaurusrea

16、cheditsfullsizeinjusteighttoelevenyears.JusteighttoelevenyearsCanyouimaginegrowingthreemetersayear?Andtheonlywayinformationlikethiscanbeworkedoutisthroughhistology,youknow?Andifthatisn'tenough,histologyhasrecentlyrevealedanothersurprise.InGermany,thebonesofseveralsmallsauropodswerefoundinaquarry.Somesauropodsgrewtobeverylarge.Thediscoveryofsmallsauropodbonesusuallymeansyouhavefoundjuvenilesyoungones.Butthehistologicalevidenceshowedthatthebon