最新改革英语六级段落匹配练习Word文档格式.docx

最新改革英语六级段落匹配练习Word文档格式.docx

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Paper--MorethanMeetstheEye

　　A）Wearesurroundedbysomuchpaperandcardthatitiseasytoforgetjusthowcomplexitis.Therearemanyvarietiesandgradesofpapermaterials,andwhilstitisfairlyeasytospotthevarieties,itisfarmoredifficulttospotthegrades.

　　B）Itneedstobeunderstoodthatmostpaperandcardismanufacturedforaspecificpurpose,sothatwhilstthecorn-flakepacketmaylooksmart,itisclearlynotsomethingdestinedforthearchives.Itismadetolookgood,butonlyneedsalimitedlifespan.Itisalsomuchcheapertomanufacturethanhighgradecard.

　　C）Papercanbemadefromanalmostendlessvarietyofcellulose-basedmaterialwhichwillincludemanywoods,cottonsandgrassesorwhichpapyrusisanexampleandfromwherewegettheword"

paper"

.Manyoftheseareveryspecialized,butthepreponderanceofpapermakinghasbeenfromsoftwoodandcottonorrags,withthebulkbeingwood-based.

　　PaperfromWood

　　D）Inordertomakewoodintopaperitneedstobebrokendownintofinestrands.Firstlybypowerfulmachineryandthenboiledwithstrongalkaliessuchascausticsoda,untilafinepulpofcellulosefibersisproduced.Itisfromthispulpthatthefinalproductismade,relyingonthebondingtogetherofthecelluloseintolayers.That,inaverysmallnutshell,istheessenceofpapermakingfromwood.However,therealityisrathermorecomplicated.Inordertogiveusourwhitepaperandcard,themakerswilladdbleachandothermaterialssuchaschinaclayandadditionalchemicals.

　　E）Afurtherproblemwithwoodisthatitcontainsamaterialthatisnotcellulose.Somethingcalledlignin.Thisisessentialforthetreesinceitholdsthecellulosefibrestogether,butifitisincorporatedintothemanufacturedpaperitpresentsarchivistswithaproblem.Lignineventuallybreaksdownandreleasesacidproductsintothepaper.Thiswillweakenthebondbetweenthecellulosefibersandthepaperwillbecomebrittleandlookratherbrownandcareworn.Wehaveallseenthisinoldnewspapersandcheappaperbackbooks.Ithasbeenestimatedthatmostpaperbackbookswillhavealifeofnotgreaterthanfiftyyears.Notwhatweneedforourarchives.

　　F）Sincethelignincanberemovedfromthepaperpulpduringmanufacture,theobviousquestionis"

whyisitleftinthepaper?

"

Theanswerliesinthefactthatligninmakesupaconsiderablepartofthetree.Byleavingthelignininthepulpapapermakercanincreasehispaperyieldfromatreetosome95%.Removingitmeansayieldofonly35%.Itisclearlyuneconomictoremovetheligninformanypaperandcardapplications.

　　G）Italsomeans,ofcourse,thatlignin-freepaperisgoingtobemoreexpensive,butthatisneverthelesswhatthearchivistmustlookforinhissupplies.Thereisnopointwhatsoeverincarefullyplacingourvaluableartifactsinpaperorcardthatisgoingtohastentheirdemise.Acidisparticularlyharmfultophotographicmaterials,causingthemtofadeandissomecasessimplyvanish!

　　H）So,howdowetellapieceofsuitablepaperorcardfromonethatisunsuitable?

Youcannotdoitbysimplylooking,andratherdisappointingly,youcannotalwaysrelyonthelabel."

Acid-free"

mightbetrueinasmuchasatestonthepapermayindicatethatitisaneutralmaterialatthistime.Butlignincantakeyearsbeforeitstartstheinevitableprocessofbreakingdown,andintherightconditionsitwillspeedupenormously.

　　I）Addedtothis,asIhaveindicatedearlier,papermayalsocontainothermaterialsaddedduringmanufacturesuchasbleach,chinaclay,chemicalwhitenersandsize.Thislookslikeableakpicture,anditwouldbebutforthefactthattherearesupplierswhowillguaranteethematerialthattheysell.Ifyouwanttobeabsolutelysurethatyouarestoringin,orprintingon,thecorrectmaterialthenthisisprobablytheonlyway.

　　J）Incidentally,acidscanmigratefrommaterialtomaterial.Liningoldshoeboxeswithgoodqualityacid-freepaperwilldolittletoguardthecontents.Theacidwillgetthereintheend.

　　PaperfromRag

　　K）Paperisalsocommonlymadefromcottonandragwaste.Thishastheadvantageofbeinglignin-free,butbecausethereismuchlesscottonandragthantrees,italsotendstobemuchmoreexpensivethanwoodpulppaper.Youwillstillneedtopurchasefromareliablesourcethough,sinceevenragpaperandcardcancontainundesirableadditives.

　　L）Areliablesourceforqualityragpapersisarecognizedartstockiest.Manywatercolorartistsinsistonusingonlyfinequalityragpaperandboard.

　　M）Themainlessontolearnfromthisinformationisthatyoucannotrelyonpurchasingarchivalmaterialsfromthehighstreet.Theonlysafesolutionistopurchasefromspecialistsuppliers.Itmaycostrathermore,butintheendyouwillknowthatyour