2468. What characters can be added here so that each character contains a part of the previous character? a) 炎 -> _ -> _ -> 紙 b) 誓 -> _ -> _ -> 鳴

a) 炎 -> 畑 -> 累 -> 紙  

炎  EN, honou - flame

畑  hatake - cultivated field

累  RUI - involvement, trouble, accumulation

紙  SHI, kami - paper

b) 誓 -> _ -> _ -> 鳴  

誓  SEI, chika(u) - swear, pledge, vow

計  KEI, haka(ru), haka(rau) - plan, total, measure

古  KO, furu(i) - old

鳴  MEI, na(ku), na(ru)(rasu) - cry, sing, howl, ring