托福听力tpo51 lecture1、2、3、4 原文+题目+答案+译文.pdf

托福听力tpo51lecture1、2、3、4原文+题目+答案+译文

Lecture11

原文1

题目3

答案5

译文6

Lecture27

原文7

题目10

答案12

译文12

Lecture314

原文14

题目16

答案18

译文18

Lecture420

原文20

题目22

答案24

译文24

Lecture1

原文

NARRATOR:Listentopartofalectureinabotanyclass.

FEMALEPROFESSOR:So,continuingwithcropdomestication,andcorn—or,um,

maize,asitsoftencalled.Obviouslyitsoneoftheworldsmostimportantcrops

today.Itssuchabigpartofthedietinsomanycountries,anditsgotsomany

differentuses,thatitshardtoimagineaworldwithoutit.Butbecauseitdoesnt

grownaturally,withouthumancultivation,andbecausetheresnoobviouswild

relativeofmaize…uh,well,forthelongesttime,researchersweren’tabletofindany

clearlinkbetweenmaizeandotherlivingplants.Andthatsmadeithardforthemto

tracethehistoryofmaize.

Now,scientifictheoriesabouttheoriginsofmaizefirststartedcomingoutinthe

1930s.Oneinvolvedaplantcalledteosinte.Teosinteisatallgrassthatgrowswildin

certainpartsofMexicoandGuatemala.Whenresearchersfirststartedlookingat

wildteosinteplants,theythoughttherewasachancethatthetwoplants—um,

maizeandteosinte—wererelated.Theyoungwildteosinteplantlooksalotlikethe

cornplant,andtheplantscontinuetoresembleeachother—atleast

superficially—evenwhentheyredeveloped.

Butwhenthescientistsexaminedthefruitsofthetwoplants,itwasadifferentstory.

Whenyoulookatripecorn,youseerowuponrowofjuicykernels…um,allthose

tinylittleyellowsquaresthatpeopleeat.Fullygrownteosinte,ontheotherhand,

hasaskinnystalkthatholdsonlyadozenorsokernelsbehindahard,um,almost

stonelikecasing.Infact,basedontheappearanceofitsfruit,teosintewasinitially

consideredtobeacloserrelativetoricethantomaize.

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