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1、Thechartbelowgivesinformationaboutglobalsalesofgamessoftware,CDsandDVDorvideo.Writeareportforauniversitylecturerdescribingtheinformation.·Youshouldwriteatleast150words.·Youshouldspendabout20minutesonthistask.modelanswer:Thechartshowsthechangesinthesalesofvideomaterial/DVDs,gamessoftw
2、areandCDsaroundtheworldinbillionsofdollarsoverathree-yearperiod.Itcanbeseenthatthesalesofvideos/DVDsandgamessoftwarehaveincreased,whilethesalesofCDshavegonedownslightly.Between2000and2003,thesaleofvideosandDVDsrosebyapproximately13billiondollars.In2000,justunder20billiondollarswortho
3、ftheseitemsweresold,butin2003,thisfigurehadrisentoalittleover30billiondollars.Thesalesofgamessoftwarealsoroseduringthisperiod,butlesssharply.Salesincreasedfromabout13billiondollarsin2000tojustunder20billiondollarsthreeyearslater.Bycontrast,duringthesametimeperiod,thesaleofCDsfellfrom
4、35billiondollarsin2000toabout32.5billiondollarsin2003. Eatingsweetfoodsproducesacidinthemouth,whichcancausetoothdecay.(HighacidlevelsaremeasuredbylowpHvalues)Describetheinformationbelowanddiscusstheimplicationsfordentalhealth.·Youshouldwriteatleast150words.·Allowyourself20minutesfort
5、histask.modelanswer:Anyonewhohasvisitedadentisthasbeentoldthateatingexcessiveamountsofsweetsrisksharmingtheteeth.ThisisbecausesweetslowerpHlevelsinthemouthtodangerouslevels.WhenthepHlevelinthemouthiskeptabove5.5,acidityissuchthatteethareunlikelytobeindangerofdecay.Sweetfoods,however,
6、causepHinthemouthtodropforatime,andthelongerpHlevelsremainbelow5.5,thegreatertheopportunityfordecaytooccur.Bycomparingfruitsugar,canesugarandhoney,whichareallcommoningredientsofsweetfoods,wefindthatcanesugarlowerspHlevelsforthelongestperiod,thusproducingthegreatestriskofthethree.Appr
7、oximatelyfiveminutesaftfterconsumingcanesugar,pHlevelsdroptoaslittleaspH3.5.Theythenbegintoriseslowly,butdonotriseabovepH5.5untilatleast30minuteshaveelapsed.Bycontrast,fruitsugar,whichcausesthemouth'saciditytofalltojustabovepH4,posesadangerforashorterperiod:toothdecayisunlikely20minu
8、tesaftercons
