[简答]  选择题　　Graffitipaintingistraditionallyadaredevilpursuit.Teenagersdodgesecurityguardstoputtheirnamesontrainsandbuses.Butoverthepastdecade,graffitihasallbutdisappearedfromBritain'scities.Between2007and2012thenumberofincidentsofgraffitirecordedbytheBritishTransportPolicefellby63%.AsurveybytheEnvironmentMinistryshowsthatfewerplacesareblightedbytagsthanever.Graffitiareincreasinglyconfinedtosanctionedwalls,suchastheStockwellballcourts.Intimethepracticemaydieoutentirely.　　Themostobviousreasonforthedeclineintaggingandtrain-paintingisbetterpolicing.NumerousCCTVcamerasmeanitishardertogetawaywithpaintingillegally.Andpunishmentsaremoresevere.Agenerationalshiftisapparent,too.Fewerteenagersaregettingintopaintingwalls.TheyprefertoplaywithiPadsandvideogames.Somehavegonetoartschoolandwanttomakemoneyfromtheirpaintings.TheInternetmeansthatpainterscanwinfarmoreattentionbypostingpicturesonlinethantheycanbybreakingintoarailwayyard.　　Taggersandgraffitiartistsmostlygrewupinthe1980sand1990s.Thosemen—andalmostallaremen—arenowolderandlesswillingtotakerisks.Graffitimayeventuallydisappear.Butfornowthehobbyisalmostrespectable.Theformergraffitiartistspaintabandonedwarehousesattheweekend.IthasbecomesomethingtodoonaSundayafternoon—aslightlyhealthieralternativetosittingandwatchingfootball.　　1.Teenagersarenotafraidofbeingcaughtbysecurityguardswhentheyputtheirnamesontrainsandbuses.　　2.Lesstagscanbefoundinpublicplacesnowadays.　　3.Becauseofbetterpolicinggraffitidecreases.　　4.Someteenagersgotoartschoolinordertolearntopaintwalls.　　5.Taggersandgraffitiartistsarestillwillingtotakerisks.