Thegroundwewalkonseemsfirm,butdeepundertheearthandunder...
问题详情：Thegroundwewalkonseemsfirm,butdeepundertheearthandundertheseatherockschangeandmove.Insomepartsoftheworldthereare“firemountains”，whichwecalltimetotimetheyburstopenandthrowoutfireandburningash....