中学生百科英语4.docx
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中学生百科英语4
中学生百科英语4——Concepts&Comments
1NavajoSandPainting
2Ceramics
3CavePaintings
4Graffiti
5TheUnitedNations
6AmnestyInternational
7UNICEF
8TheOlympicMovement
9Hawaii
10Deserts
11Antarctica
12NationalParks
13Satellites
14Comets
15MotorVehicles:
TheProsandCons
16NewPlants
17UpinSmoke
18Memory
19Obesity:
TheNewEpidemic
20CanFashionBeHazardoustoYourHealth
1NavajoSandPainting
Morethan500yearsagotheancestorsoftheNavajopeopleleftthecoldnorthernregionthatisnowpartofwesternCanadaandAlaskaandmigratedsouthtowhatisnowthesouthwesternpartoftheUnitedStates.TheareainwhichtheNavajofinallysettledismainlydesert.Itisaharshenvironmentthatgetslittlerain.
Theanimalsandplantsthatlivetherehavehadtoadaptinordertosurviveintheunforgivingclimateandlandscape.
WhentheNavajoarrivedinthearea,theytoohadtoadapttotheharshdesertconditionsinordertosurvive.Theyhadtolearntomakeuseofthenaturalresourcesintheirenvironmenttoprovidefortheirshelter,food,andothernecessities.Overtime,theNavajobecamefamousforthethingstheywereabletocreatefromthenaturalresourcesathand.OneofthemostfamousNavajocreationsiscalledsandpainting.Mostpeoplethinkofapaintingasaworkofart.FortheNavajo,however,sandpaintingisnotartwork.Rather,sandpaintingisanimportantpartofareligiousceremony.Themakingofasandpaintingispartofahealingceremonythatissupposedtorestorethehealthandwell-beingofasickperson.
TheonlypeoplewhoareallowedtocreatesandpaintingsarespeciallytrainedNavajo"singers''or"medicinemen"andtheirassistants.ANavajosingerbeginstheprocessofcreatingasandpaintingbycollectingdifferentrocks.Therocksarethencrushedandgroundintosand.Traditionally,aNavajosingerandhisassistantsmakethesandpaintingonthefloorofasmallNavajohousecalledahogan.Workingunderthedirectionofthesinger,theassistantstakecoloredsandintheirhandsanddripitonthefloorinaline.Usingdifferentcolors,theyslowlymakeapicture.
ThesizeofNavajosandpaintingsvaries.Asmallsandpaintingislessthanameterwide,whilealargesandpaintingcanbeover6meterswide.Thenumberofpeopleassistingthesingeralsovaries.Asmallsandpaintingmayhave2or3peopleworkingonitandtakeanhourtocomplete,whilealargepaintingmayrequire10menandwomenandtakealldaytofinish.
Duringthehealingceremony,thesickpersonmovesontothecompletedsandpainting.Thesickpersonsitsdirectlyonthesandpaintingsothatitcanserveasapathwayforevilorillnesstoleavetheperson'sbodyandforgoodnessorhealthtoreturntoit.ThisexplainswhytheNavajowordforsandpaintingmeans"placewherethegodscomeandgo."Afterthesickpersonhasbeentreated,othervisitorsmaygouptothepaintinganddabsomeofthesandonthemselvessothatthesandpaintingbringshealthandwellbeingintotheirlivestoo.
Attheendofthehealingceremony,itisimperativethatthesandpaintingbedestroyed.TheNavajobelievethatsomethingterriblewillhappeniftheyfailtodestroyasandpaintingproperly.So,inthereverseoftheorderinwhichitwasmade,thesingersweepsthepaintingawayandreturnsthesandtothelandscape.
Navajosingersmaketheirsandpaintingsfrommemory,andtheyalwaysmakethesamepicturesinexactlythesameway.Therearebetween600and1,000differentpicturesforsandpaintings.Atonepointinhistory,therewasonesingerforevery150Navajos.Today,theratioismuchlower,withonesingerforroughlyevery2,200people.Onereasonforthischangeistheextensivetrainingrequiredtoperformthedutiesofasinger;itcantakeaslongas14yearstotrainsomeone.Asecondreasonforthechangeinratioisthatasingercantrainonlyonestudentatatime.Thisneedforone-on-onetraininghaslimitedthenumberofstudentswhocanbetrained.
WhileatruesandpaintingispartofaNavajoceremonyandlastsforonlyashorttime,sandpaintingasapermanentartformhasalsodeveloped.Thefirstpermanentsandpaintingsappearedintheearly1900s.Theseearlypiecesofartwereactuallytapestriesratherthanpaintingsmadewithsand.ThetapestrieswerewovenbyarespectedNavajosingernamedHosteenKlah,whocopiedthepicturesfromsandpaintings.However,toavoidcausingsomethingterribletohappenbymakingapermanentpicture,Klahnevermadethepictureexactlythesameastheoriginal.HewouldnotuseaNavajopicturewithoutchangingitalittle.Beforelong,touristsintheareasawKlah'sweavingsandaskedtobuythem.Klahfinallyagreedtoselloneofhisweavingsifthebuyerpromisednevertoputitonthefloororwalkonit.
Inthe1930s,theNavajobegancreatinganothertypeofpermanentsandpainting.Theymadethesepermanentpaintingsbyslowlydrippingcoloredsandontoglue-coveredboards.Today,thesesandpaintingsareconsideredtobeworksofartratherthanpartofareligiousceremony.Theyaremadebyartistsratherthansingers,andtheyappearinartshowsandinartmuseums.
Thereisstillcontroversyoverthesellingofsandpaintings.SomeNavajossaythatsandpaintingsarepartoftheirreligionandshouldnotbesold.Butothersbelievethattheartists'changestothepicturesprotecttheirreligiouspower.
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2Ceramics
Themostancientartifactsinourpossessiontodayweremadeoutofclaymanythousandsofyearsago.Infact,muchofwhatwenowknowaboutculturesofthepastwelearnedbystudyingpiecesoftheirclaydishesandclayfigures.Veryfewthingsmadefromothermaterialshavesurvivedtotellusabouttheculturesthatproducedthem.
ObjectsmadefromclaycametobecalledceramicsfromtheGreekwordceramics,whichmeans"potter'sclay."Ceramicsaredividedintomanydifferentkindsbasedonthetypeofclayusedandhowtheclayisfired.Themostcommontypesofceramicsarepottery,stoneware,andporcelain.Tomakepottery,forexample,clayisfiredatabout500C.Clayfired°atabout1200Cbecome°sstoneware.Whenwhiteclayisfiredatanevenhighertemperature,itbecomesporcelain.Bakingtheclayatsuchhightemperaturesactuallychangesthestructureoftheclaysothatitbecomespermanentlyhardandalmostindestructible.Theartofmakingpotterydevelopedinmanyplacesaroundtheworld.Someoftheearliestpiecesofpotterywereprobablymadewhenpeopletriedtostrengthenbasketswovenofgrassandsticks.SomearcheologiststhinkthatearlypottersinChinamayhavecoveredtheinsideofwovenbasketswithclaysothatthebasketswouldholdwater.Whenthebasketswereeitherplacedonafireorlefttherebymistake,thefireburnedthegrassawayandturnedthebasketsintohard,durablepots.
Earlypottersindifferentpartsoftheworldfoundinterestingwaystodecoratetheirworktomakeitmoreattractive.Theyscratchedthesurfaceofthesoftclaytomakedecorativelinesanddesigns.Theyalsousedglazes,whichareaspecialkindofpaint,tomakeclayobjectssmooth,shiny,andcolorful.TheEgyptianswerealreadydecoratingtheirpotterywithcolorsanddesignsabout5,000yearsago.
SimilarstylesbegantospreadthroughouttheMediterranean,region.By3,500yearsago,thepeopleoftheGreekislandofCretewereproducingtheirownpotterydecoratedwithdesignsandimagesofanimals.ThesedesignssurvivedthousandsofyearsandcanstillbeseeninexamplesofancientGreekart.ThepotterymakersofChinawerethefirsttolearntomakeporcelain,whichisthefinestandmostfragiletypeofpottery.Ifyouholdapieceofporcelainupintheair,lightwillshinethroughit.TheChineseexportedporcelaintoEurope,whereitbecamehighlyvalued.Formanyyears,EuropeanpotterstriedtocopyChineseporcelain,butitwasnotuntil1710thataGermanscientistfinallylearnedhowtomakeit.Bytheendofthe18thcentury,otherEuropeancountrieswerealsoproducingporcelain,andtodayFranceandEnglandproducesomeofthefinestporcelainintheworld.
Therearedifferentwaystoformaclaydishorbowl.Theeasiestmethodistosimplyhollowoutaclayball,usingyourhands.Anothersimplemethodistorolltheclayintoalong"rope"andthenwinditintoashape.Athirdmethodistospreadtheclayaroundsomething.Theinventionofthepotter'swheelmorethan5,000yearsagointroducedanentirelynewwaytoformaclayobject.Withthismethod,thepotterplacessomeclayinthecenterofaround,flatwheelthatcanturnveryfast.Asthewheelturns,thepotteruseshisorherhandstoshapetheclay.
Usingapotter'swheelmakesitpossibletoformclayobjectsthataresmootherandmoreuniformlyround.Aclayobjectisusuallydecoratedfirstandthenbaked.Bakingtheclayatveryhightemperaturesmakesithardandstrong.Firingalsomakestheglazesticktothepottery.Whenthefiringiscompleted,thepottermustcarefullyremovethepotteryfromtheovenandletitcoolslowly.Ifitcoolstooquickly,itcouldcrackandbreak.
Overtheyears,clayobjectshaveservedmanypurposes.Obviously,oneofthemostcommonusesofpotteryisforhouseholddishes.Becausepotteryisstrongandwaterproof,itmakesanexcellentdishtorcarrying,storing,cooking,andservingfood.Firedclayhasalsobeenusedtomakebricksforbuildinghousesandtomaketilestorcoveringfloors.Ceramicsarealsoincrediblyheatresistant,sotheycanbeusedwheremetalwouldmeltorbecomeweak.Today,ceramicsareimportantinindustryandengineering.Onerarelydiscusseduseofceramicsisforburialceremonies.Insomecultures,specialceramicobjectswereburiedalongwiththed