Doyoulikelisteningtomusic？Doyouoftenturnupthemusicwhenyou'reusingearphones？Ifso，yourhearingmayhavebeendamaged（损坏）．TheWorldHealthOrganization（WHO）isworriedthat1.1billionchildrenandyoungpeopl

　　Doyoulikelisteningtomusic？Doyouoftenturnupthemusicwhenyou'reusingearphones？Ifso，yourhearingmayhavebeendamaged（损坏）．

　　TheWorldHealthOrganization（WHO）isworriedthat1.1billionchildrenandyoungpeoplearedamagingtheirhearingbylisteningtoloudmusic．Nearlyhalftheyoungpeopleindevelopedcountriesmaylosetheirhearingbecauseofthe"unsafeuse"ofmusicplayers，includingsmartphones．Loudmusicinnightclubs，partiesandatsportsalsomakeitworse．TheWHOadvisesyoungpeopletolistentomusicforjustonehouraday．Dr．EtienneKrugtoldBBC："Whatwe'retryingtodoistodrawpeople'sattentiontoaproblemthatisnottalkedaboutenough．"Hesaidit'seasytosolvethisproblem．

　　Dr．Krugsaidkeepingthemusicdownandlimiting（限制）thelisteningtimetolessthanonehouradaywouldsavealotofpeople'shearing．However，healsosaid，"Evenanhourcanbetoomuchifthemusicistooloud．"RalphHolme，aresearcher，explainedhowloudnoisecandamageears．Hesaid："Loudsoundsdamageyourhearingbykillingoffthousandsoflittlehaircells（细胞）intheinnerear．Thecellscantelldifferentsoundsthroughvibration（振动）．Buttheyareveryfragile-theygetdamagedeasilyandevendieiftheyvibratetoomuchbecauseofloudsoundsfortoolong．"Hewarned："Thebiggerproblemistheydon'tgrowbackandtheearcannolongergetsound．"

　　Noonewantstolosetheirhearing!Therefore，nexttimewhenyoulistentomusic，makesureit'snottooloudandonlylistenforlessthananhour．Youcanenjoyyourmusicmuchbetterinthisway．

　　49．Howarethechildrenandyoungpeopledamagingtheirhearing？___．

　　A．Byusingsmartphones．

　　B．Bygoingtotheparty．

　　C．Bylisteningtoloudmusic．

　　D．Bytalkingwithfriends．

　　50．HowlongdoesWHOadviseyoungpeopletolistentomusicaday？___

　　A．Foralongtime．

　　B．Forjustonehour．

　　C．Forhalfoftheday．

　　D．Formorethanonehour．

　　51．Whatdoestheword"fragile"inParagraph3probablymean？___

　　A．Weak．

　　B．Clever．

　　C．Small．

　　D．Strong．

　　52．Fromthepassagewecanlearnthat___．

　　A．keepingth