quEstions 16-20 who CAn tAkE pArt in EACh oF thE ClAssEs writE thE CorrECt lEttErA, B、or C、nExt to quEstions 16-20. ClAss pArtiCipAnts A、ChilDrEn AnD tEEnAgErs B、ADults C、All AgEs quEstions 16-20 who CAn tAkE pArt in EACh oF thE ClAssEs writE thE CorrECt lEttErA, B、or C、nExt to quEstions 16-20. ClAss pArtiCipAnts A、ChilDrEn AnD tEEnAgErs B、ADults C、All AgEs