资源描述：
《托福tpo小作文范文(3,4,9,10)》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、TPO9Thelecturerpointsoutseveralproblemswiththeuseofhydrogen-basedfuel-cellenginesinsupportofherclaimthatsubstitutingthemforinternal-combustionenginesistechnologicallyunfeasible,environmentallyunfriendly,andeconomicallyunviable.First,thelecturerstatesthatitisimpracticaltoreplaceinternal-combustionen
2、gineswithfuel-cellenginesbecauseusingthelatterrequireshydrogeninapureliquidform,whichistechnologicallychallengingtobothobtainandstore.However,thereadingarguesthatbecausehydrogencanbeextractedfrommanyresourcesincludingwater,fuelcellenginespoweredbythisinfinitesourceofenergyareanextremelyattractiveal
3、ternative.Second,thelecturerrefutestheclaiminthereadingthathydrogencellsareenvironmentallyfriendly.Shearguesthatalthoughenginesthatusehydrogencellsproducelesspollution,themanufacturingofhydrogencellsgenerateslargeamountsofharmfulby-productsduetotheburningoffossilfuelsinthepurificationprocess.Third,
4、althoughthereadingsuggeststhathydrogen-basedenginesaremorefuel-efficientandthuseconomicallycompetitivethaninternal-combustionengines,theprofessorarguesthatsuchanadvantageisunderminedbythefactthatfuel-cellenginesareextremelyexpensivetomanufacturebecausetheyrequiretheadditionofplatinum,averyrareandex
5、pensivematerial.TPO10Thelecturerandthereadingpassagesuggesttwocompetingtheories,thepredationtheoryvs.thepollutiontheory,toexplainwhytheseaotterpopulationisinrapiddecline.Theprofessorreasonsthattheabsenceofdeadseaotterswashedupthecoastsuggeststhattheirdeclineisnotcausedbyseapollutionbutratherbyseapr
6、edatorswhoconsumetheirbodiesafterKillingthem.Incontrast,thereadingpassageattributesthedeathofseaotterstopollution,citingevidenceofincreasedsourcesofoceancontaminantswhichleadtogreatervulnerabilitytoinfections.Furthermore,thelecturerarguesthatorcasarelikelyfactorsinthedisappearanceofseaotters,becaus
7、ethescarcityofwhales,theirusualprey,hasleftthemwithnootherchoicebuttostarthuntingsmallermammalsliketheottersforfood.Thereadingpassage,ontheotherhand,Rulesoutthistheorybasedontheorca’spreyinghabit,andinstead
