-----0308托福试题阅读（55minutes）Question1-11Iffoodisallowedtostandforsometime,itputrefies.Whentheputrefiedmaterialisexaminedmicroscopically,itisfoundtobeteemingwithbacteria.Wheredothesebacteriacomefrom,sincetheyarenotseeninfreshfood?Evenuntilthemid-nineteenthcentury,manypeoplebelievedthatsuchmicroorganismsoriginatedbyspontaneous(5)generation,ahypotheticalprocessbywhichlivingorganismsdevelopfromnonlivingmatter.ThemostpowerfulopponentofthetheoryofspontaneousgenerationwastheFrenchchemistandmicrobiologistLouisPasteur(1822-1895).Pasteurshowedthatstructurespresentinaircloselyresemblethemicroorganismsseeninputrefyingmaterials.Hedid(10)thisbypassingairthroughguncottonfilters,thefibersofwhichstopsolidparticles.Aftertheguncottonwasdissolvedinamixtureofalcoholandether,theparticlesthatithadtrappedfelltothebottomoftheliquidandwereexaminedonamicroscopeslide.Pasteurfoundthatinordinaryairtheseexistsavarietyofsolidstructuresranginginsizefrom0.01mmtomorethan1.0mm.Manyofthesebodiesresembledthereproductive(15)structuresofcommonmolds,single-celledanimals,andvariousothermicrobialcells.Asmanyas20to30ofthemwerefoundinfifteenlitersofordinaryair,andtheycouldnotbedistinguishedfromtheorganismsfoundinmuchlargernumbersinputrefyingmaterials.Pasteurconcludedthattheorganismsfoundinputrefyingmaterialsoriginatedfromtheorganizedbodiespresentintheair.Hepostulatedthatthesebodiesareconstantly(20)beingdepositedonallobjects.Pasteurshowedthatifanutrientsolutionwassealedinaglassflaskandheatedtoboilingtodestroyallthelivingorganismscontaminatingit,itneverputrefied.Theproponentsofspontaneousgenerationdeclaredthatfreshairwasnecessaryforspontaneousgenerationandthattheairinsidethesealedflaskwasaffectedinsomeway(25)byheatingsothatitwouldnolongersupportspontaneousgeneration.Pasteurconstructedaswan-neckedflaskinwhichputrefyingmaterialscouldheheatedtoboiling,butaircouldreenter.Thebendsintheneckpreventedmicroorganismsfromgettingintheflask..Materialsterilizedinsuchaflaskdidnotputrefy.1,Whatdoe