历年托福考试阅读真题汇总含答案解析

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1、0308托福试题阅读（55minutes）Question1-11Iffoodisallowedtostandforsometime,itputrefies.Whentheputrefiedmaterialisexaminedmicroscopically,itisfoundtobeteemingwithbacteria.Wheredothesebacteriacomefrom,sincetheyarenotseeninfreshfood?Evenuntilthemid-nineteenthcentury,manype

2、oplebelievedthatsuchmicroorganismsoriginatedbyspontaneous(5)generation,ahypotheticalprocessbywhichlivingorganismsdevelopfromnonlivingmatter.ThemostpowerfulopponentofthetheoryofspontaneousgenerationwastheFrenchchemistandmicrobiologistLouisPasteur(1822-1895).Paste

3、urshowedthatstructurespresentinaircloselyresemblethemicroorganismsseeninputrefyingmaterials.Hedid(10)thisbypassingairthroughguncottonfilters,thefibersofwhichstopsolidparticles.Aftertheguncottonwasdissolvedinamixtureofalcoholandether,theparticlesthatithadtrappedf

4、elltothebottomoftheliquidandwereexaminedonamicroscopeslide.Pasteurfoundthatinordinaryairtheseexistsavarietyofsolidstructuresranginginsizefrom0.01mmtomorethan1.0mm.Manyofthesebodiesresembledthereproductive(15)structuresofcommonmolds,single-celledanimals,andvariou

5、sothermicrobialcells.Asmanyas20to30ofthemwerefoundinfifteenlitersofordinaryair,andtheycouldnotbedistinguishedfromtheorganismsfoundinmuchlargernumbersinputrefyingmaterials.Pasteurconcludedthattheorganismsfoundinputrefyingmaterialsoriginatedfromtheorganizedbodiesp

6、resentintheair.Hepostulatedthatthesebodiesareconstantly(20)beingdepositedonallobjects.Pasteurshowedthatifanutrientsolutionwassealedinaglassflaskandheatedtoboilingtodestroyallthelivingorganismscontaminatingit,itneverputrefied.Theproponentsofspontaneousgenerationd

7、eclaredthatfreshairwasnecessaryforspontaneousgenerationandthattheairinsidethesealedflaskwasaffectedinsomeway(25)byheatingsothatitwouldnolongersupportspontaneousgeneration.Pasteurconstructedaswan-neckedflaskinwhichputrefyingmaterialscouldheheatedtoboiling,butairc

8、ouldreenter.Thebendsintheneckpreventedmicroorganismsfromgettingintheflask..Materialsterilizedinsuchaflaskdidnotputrefy.1,Whatdoesthepassagemainlydiscuss?(a)Pasteur’si