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1、.Thechartbelowgivesinformationaboutglobalsalesofgamessoftware,CDsandDVDorvideo.Writeareportforauniversitylecturerdescribingtheinformation.·Youshouldwriteatleast150words.·Youshouldspendabout20minutesonthistask.modelanswer:Thechartshowsthechangesinthes
2、alesofvideomaterial/DVDs,gamessoftwareandCDsaroundtheworldinbillionsofdollarsoverathree-yearperiod.Itcanbeseenthatthesalesofvideos/DVDsandgamessoftwarehaveincreased,whilethesalesofCDshavegonedownslightly.Between2000and2003,thesaleofvideosandDVDsroseb
3、yapproximately13billiondollars.In2000,justunder20billiondollarsworthoftheseitemsweresold,butin2003,thisfigurehadrisentoalittleover30billiondollars.Thesalesofgamessoftwarealsoroseduringthisperiod,butlesssharply.Salesincreasedfromabout13billiondollarsi
4、n2000tojustunder20billiondollarsthreeyearslater.Bycontrast,duringthesametimeperiod,thesaleofCDsfellfrom35billiondollarsin2000toabout32.5billiondollarsin2003. Eatingsweetfoodsproducesacidinthemouth,whichcancausetoothdecay.(Highacidlevelsaremeasuredbyl
5、owpHvalues)Describetheinformationbelowanddiscusstheimplicationsfordentalhealth...·Youshouldwriteatleast150words.·Allowyourself20minutesforthistask.modelanswer:Anyonewhohasvisitedadentisthasbeentoldthateatingexcessiveamountsofsweetsrisksharmingtheteet
6、h.ThisisbecausesweetslowerpHlevelsinthemouthtodangerouslevels.WhenthepHlevelinthemouthiskeptabove5.5,acidityissuchthatteethareunlikelytobeindangerofdecay.Sweetfoods,however,causepHinthemouthtodropforatime,andthelongerpHlevelsremainbelow5.5,thegreater
7、theopportunityfordecaytooccur.Bycomparingfruitsugar,canesugarandhoney,whichareallcommoningredientsofsweetfoods,wefindthatcanesugarlowerspHlevelsforthelongestperiod,thusproducingthegreatestriskofthethree.Approximatelyfive..minutesaftfterconsumingcanes
8、ugar,pHlevelsdroptoaslittleaspH3.5.Theythenbegintoriseslowly,butdonotriseabovepH5.5untilatleast30minuteshaveelapsed.Bycontrast,fruitsugar,whichcausesthemouth'saciditytofalltojustabovepH4,posesadangerforashorterperiod:toothdecayisunlikely20minutesafte
