历托福考试阅读高频真题汇总【含答案】

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1、智课网TOEFL备考资料7/7历年托福考试阅读高频真题汇总【含答案】摘要：之前我们已经上传了历年来托福阅读考试的真题题目，今天小编接着为大家介绍一些托福阅读考试过程中经常遇到的一些真题类型，这些题目全部是精华内容，非常值得大家拥有。历年托福考试阅读高频真题依次从上到下，出题频率由高到低，下面我们现将其中的一篇出题率极高的文章内容分享给你。Iffoodisallowedtostandforsometime,itputrefies.Whentheputrefiedmaterialisexaminedmicroscopic

2、ally,itisfoundtobeteemingwithbacteria.Wheredothesebacteriacomefrom,sincetheyarenotseeninfreshfood?Evenuntilthemid-nineteenthcentury,manypeoplebelievedthatsuchmicroorganismsoriginatedbyspontaneousgeneration,ahypotheticalprocessbywhichlivingorganismsdevelopfromno

3、nlivingmatter.ThemostpowerfulopponentofthetheoryofspontaneousgenerationwastheFrenchchemistandmicrobiologistLouisPasteur(1822-1895).Pasteurshowedthatstructurespresentinaircloselyresemblethe.microorganismsseeninputrefyingmaterials.Hedidthisbypassingairthroughgunc

4、ottonfilters,thefibersofwhichstopsolidparticles.Aftertheguncottonwasdissolvedinamixtureofalcoholandether,theparticlesthatithadtrappedfelltothebottomoftheliquidandwereexaminedonamicroscopeslide.Pasteurfoundthatinordinaryairtheseexistsavarietyofsolidstructuresran

5、ginginsizefrom0.01mmtomorethan1.0mm.Manyofthesebodiesresembledthereproductivestructuresofcommonmolds,single-celledanimals,andvariousothermicrobialcells.Asmanyas20to30ofthemwerefoundinfifteenlitersofordinaryair,andtheycouldnotbedistinguishedfromtheorganismsfound

6、inmuchlargernumbersinputrefyingmaterials.Pasteurconcludedthattheorganismsfoundinputrefyingmaterialsoriginatedfromtheorganizedbodiespresentintheair.Hepostulatedthatthesebodiesareconstantlybeingdepositedonallobjects.7/7Pasteurshowedthatifanutrientsolutionwasseale

7、dinaglassflaskandheatedtoboilingtodestroyallthelivingorganismscontaminatingit,itneverputrefied.Theproponentsofspontaneousgenerationdeclaredthatfreshairwasnecessaryforspontaneousgenerationandthattheairinsidethesealedflaskwasaffectedinsomewaybyheatingsothatitwoul

8、dnolongersupportspontaneousgeneration.Pasteurconstructedaswan-neckedflaskinwhichputrefyingmaterialscouldheheatedtoboiling,butaircouldreenter.Thebendsintheneckpreventedmicroo