Longagomenlearnedthattheworldofnatureisbuiltwithmathematicalexactnessaccordingtorefinedandpowerfullaws;everybeestokesitswingsexactly440timesasecondtopropelitselffortymilesanhour;theeyeofeveryflyhasexactly7,000lenses;everyspider′sthreadiscomposedof300singlethreads. Theprogressofcivilizationitselfcanbemeasuredbyitsrangeofmathematics.TheearlyEgyptiansknowenoughofgeometrytobuildthepyramidsandtheGreeksusedtrigonometrytomeasurethecircumferenceoftheearthtwothousandyearsbeforeColumbussailed.EuropeancivilizationcombinedgeometryandtrigonometrywiththedecimalsystemoftheArabstoproducethemapswithwhichtheEuropeanexploredtheworld.Inalatercentury,mathematiciansstudiedthependulum(钟摆)ofthenewlyinventedclockandcreatedthelanguageofcalculustomeasuremotion. Theyardstickofmeasurementtodaymustcovereverythingfromunitstinierthanatomstodistanceofmillionsoflightyears.Speedandaccuracyarevital.MancanneversendarackettoMarsunlessheknowstheexactdistancetotheplanet.Sincetheslightesterrorcouldmeanmissingitby30,000miles.Innavigatingamidtheplanetsandstars,manmusthavethehelpofsomekindofmachinecalculatorsforfastandabsolutelyaccurateinformation. Howisthesecondparagraphdeveloped?
A.By contrast. B.By classification. C.By making assumption. D.By giving example.正确答案D
