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1、Thechartbelowgivesinformationaboutglobalsalesofgamessoftware,CDsandDVDorvideo.Writeareportforauniversitylecturerdescribingtheinformation.·Youshouldwriteatleast150words.·Youshouldspendabout20minutesonthistask.modelanswer:Thechartshowsthechangesinthesalesofvideomaterial/D
2、VDs,gamessoftwareandCDsaroundtheworldinbillionsofdollarsoverathree-yearperiod.Itcanbeseenthatthesalesofvideos/DVDsandgamessoftwarehaveincreased,whilethesalesofCDshavegonedownslightly.Between2000and2003,thesaleofvideosandDVDsrosebyapproximately13billiondollars.In2000,jus
3、tunder20billiondollarsworthoftheseitemsweresold,butin2003,thisfigurehadrisentoalittleover30billiondollars.Thesalesofgamessoftwarealsoroseduringthisperiod,butlesssharply.Salesincreasedfromabout13billiondollarsin2000tojustunder20billiondollarsthreeyearslater.Bycontrast,du
4、ringthesametimeperiod,thesaleofCDsfellfrom35billiondollarsin2000toabout32.5billiondollarsin2003. Eatingsweetfoodsproducesacidinthemouth,whichcancausetoothdecay.(HighacidlevelsaremeasuredbylowpHvalues)Describetheinformationbelowanddiscusstheimplicationsfordentalhealth.·Y
5、oushouldwriteatleast150words.·Allowyourself20minutesforthistask.modelanswer:Anyonewhohasvisitedadentisthasbeentoldthateatingexcessiveamountsofsweetsrisksharmingtheteeth.ThisisbecausesweetslowerpHlevelsinthemouthtodangerouslevels.WhenthepHlevelinthemouthiskeptabove5.5,ac
6、idityissuchthatteethareunlikelytobeindangerofdecay.Sweetfoods,however,causepHinthemouthtodropforatime,andthelongerpHlevelsremainbelow5.5,thegreatertheopportunityfordecaytooccur.Bycomparingfruitsugar,canesugarandhoney,whichareallcommoningredientsofsweetfoods,wefindthatca
7、nesugarlowerspHlevelsforthelongestperiod,thusproducingthegreatestriskofthethree.Approximatelyfiveminutesaftfterconsumingcanesugar,pHlevelsdroptoaslittleaspH3.5.Theythenbegintoriseslowly,butdonotriseabovepH5.5untilatleast30minuteshaveelapsed.Bycontrast,fruitsugar,whichca
8、usesthemouth'saciditytofalltojustabovepH4,posesadangerforashorterperiod:toothdecayisunlikely20minutesaftercons
