中学生百科英语4.docx

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,othervisitorsmaygouptothepaintinganddabsomeofthesandonthemselvessothatthesandpaintingbringshealthandwell-beingintotheirlivestoo.

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.

（913words）

2Ceramics

Themostancientartifactsinourpossessiontodayweremadeoutofclaymanythousandsofyearsago.Infact,muchofwhatwenowknowaboutculturesofthepastwelearnedbystudyingpiecesoftheirclaydishesandclayfigures.Veryfewthingsmadefromothermaterialshavesurvivedtotellusabouttheculturesthatproducedthem.

ObjectsmadefromclaycametobecalledceramicsfromtheGreekwordceramics,whichmeans"potter'sclay."Ceramicsaredividedintomanydifferentkindsbasedonthetypeofclayusedandhowtheclayisfired.Themostcommontypesofceramicsarepottery,stoneware,andporcelain.Tomakepottery,forexample,clayisfiredatabout500°C.Clayfiredatabout1200°Cbecomesstoneware.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,specialceramicobjectswerebu