以how is glass made 为题弄一篇小短文,朗读2分钟左右
Innature,glasscanbeformedinthreeways:
1.Whenlightningstrikessand–Theenergyfromlightningthatstrikesasandybeachorsandysoilfusesnaturalsilicaglass(calledlechatelierite)intofragileformscalledfulgurites.Thesebranch-likeformationsinthegroundcanrangefromtwocentimeterstothreeinchesindiameter,anduptoseveralfeetlong.Thetanorgrayishexteriorofafulguriteiscrustyandsandy,buttheinteriorislinedwithbubblyglass.SandfulguritesarecommonlyfoundinFlorida—astatewithahighnumberoflightningstrikes—theshoresofLakeMichigan,andtheAtlanticcoast.Fulguritesareveryfragilesomustbecarefullyexcavated.
2.Whenlightningstrikesrocks–Rockfulguritesareformedwhenlightingstrikesarockysurface,andthiscommonlyoccursonmountainpeaks.Ratherthanthebranch-likeformofasandfulgurite,arockfulguriteappearsasathin,glassycrustontherock’ssurface.Ithasglass-linedbubblesorcavities.Theglasshaslesssilicathaninsandfulgurites,andthecolorsareinfluencedbythemineralcompositionoftherockthatwasstruck.
3.WhenameteoritecollideswithEarth–AnothernaturalphenomenonthatcreatesglassiswhenameteoritestrikesEarth.Partsoftheoutercrustareheatedandsuddenlycooledatimpact,formingsmallobjects,calledtektites,whicharescatteredintoenormousdebrisfields.Theycontainapproximately70percentsilica.Scientistsfirstthoughttektites,whicharefrom800,000toover64millionyearsold,originatedfromspace,butnowunderstandthattheyweremostlikelysedimentaryrocksonEarth.ItisinterestingthattektitesarefoundonallcontinentsexceptAntarcticaandSouthAmerica,andtheirsize,shapeandcompositionvarydependingontheregionsinwhichtheyarefound.Sometektitesarelocatedinornearlargecraters,othersmixedinwithordinarygravelandcoarsesediment.
AtomicBombFormedGlass
Onewaythatglasswasformednaturallybutwithman’sinfluencewasthroughthefirstatomicexplosion.WhenthenuclearbombwasdetonatedinNewMexicoin1945,thecraterthatitformedbecamecoatedwithagrayish-greencoloredsilicaglassthatwascalled“trinitite”becausethetestwasconductedatTrinitySite.Theextremeheatoftheexplosionhadmeltedsandintheremote,desertlocationandconvertedittoglass.
TheBasicIngredientsManUsestoMakeGlass
Tomakeglass,peopleuseabasicrecipeofsand(silicondioxide),sodaash(sodiumcarbonate)andlimestone(calciumcarbonate).ThepeoplesofancientMesopotamiaprobablyinadvertentlymadeglassforthefirsttimewhentheyfiredpottery,asthesandandmineralswerefusedtoaglazeontheirpieces.Inancientdays,themineralnatron(hydratedsodiumcarbonate)—whichwasusedinembalmingandceramics—wasusedforthesodaash.
Beforemanlearnedthesecretofglassmaking,naturewastheworld'sonlyglassmaker.Lightningstrikingsandmelteditintolong,thintubesofglass,andvolcanoeseruptingmeltedrocksandsandintoglass.
Man'searliestglasswasprobablyaglazeonceramicpotterymadesomewherearound3000B.C.
Today,threeinexpensiveingredients,sand,sodaash,andlime,aremeltedtogethertomakeglass.Thisisdoneinlargefurnacesathightemperaturesuntilthemixturebecomeasyrupymass.Whenthissyrupcools,itisglass.
Whenglassisinameltedstate,itcanbeshapedbymanymethods,butthemostcommonareblowing,pressing,anddrawing.
Blowingistheoldestmethodofworkingwithglass,datingbackthousandsofyears.Aballofmolten,ormelted,glassisputontheendofahollowironpipe,andaworkerblowsgentleintothepipe(muchlikethewayyoublowsoapbubbles)untiltheglasstakestheshapeandthinnesstheblowerwants.Duringthisprocess,theglassisconstantlyreheatedtokeepitsoftandworkable.
Whentheglassisshapedtotheblower'ssatisfactionintoabottleoravase,itisbrokenfromthepipe.Althoughglassblowingbyhandisstilldonetoday,itcanalsobedonebymachine.
Inthepressingmethod,ahotglobofglassisdroppedintoamold,thenpressedwithatool,sotheglassfillstheinsideofthemold.Ashrays,bakingdishes,andglasscontainersaremadethisway.
Thedrawingmethodshapesglassflat,asforwindowsandmirrors,orintotubes,asforfluorescentlights,TVtubes,andlaboratoryequipment.Tomakeflatglass,firstthemeltedglassisdrawnintoatankofmeltedtin.Thetin'sperfectlysmoothsurfaceformsasmoothlayerofglassastheglassfloatsontopofthetin.Tomakeglasstubing,astreamofmoltenglassisdrawnaroundtheinsideofacylinder.Asthecylinderrotates,airisblownthroughit,formingacontinuoustubeoutoftheglass.
Nomatterwhichmethodisused,theglassmuststillgothroughaprocesscalledannealing.Inannealing,theglassisreheatedandgraduallycooledtorestoreitsstrengthandpreventitsshattering.Temperingisalsousedtostrengthenglass.Intempering,theglassisreheated,thenchilledbysuddenblastsofcoldair.
Thisprocessshouldnotbeconfusedwithanothermethodcalledlampworking,inwhichfinishedglasstubesareheatedoverablowtorch,andastheglassworkerbends,twists,andstretchestheglass,hecancreateminiatureanimals,ships,andbaskets.
Banks,tanks,aircraft,andsomegovernmentcarshaveglasssothickandwithsomanylayersthatitcanstopabulletevenatcloserange!
salt改为形容词
salty
释义：含盐的;咸的;用盐腌的;粗俗的;猥亵的;粗鲁的;爱闹事的;挑衅的
读音：英[ˈsɔːlti]美[ˈsɔːlti]
例句：
Salttakesinplentyofwater,somostbacteria(细菌)cannotliveinasaltyenvironment.
盐会吸收大量水分，因此大多数细菌无法在含盐环境中生存。
Itistoosaltytodrink.
太咸了，不能喝。
Theycantakerefugeinthelesssaltywaters.
他们可以在咸度较低的水域避难。
Theyeatalotofmeatanddrinksaltytea.
他们吃很多肉，喝咸茶。
AslesssaltylagoonsformontheouteredgesfromhotspringsflowingintoLakeNatron.
因为流入纳特隆湖的温泉在湖外边缘形成了不太咸的泻湖。
