2438. What characters can be added here so that each character contains a part of the previous character? a) 菓 -> _ -> _ -> 肪 b) 誓 -> _ -> _ -> 館

a) 菓 -> 棋 -> 期 -> 肪  

菓  KA - cake, fruit

棋  KI - go, shogi, Japanese chess

期  KI, GO - time, period, term

肪  BOU - animal fat

b) 誓 -> 詳 -> 養 -> 館  

誓  SEI, chika(u) - swear, pledge, vow

詳  SHOU, kuwa(shii) - detailed, full, familiar with

養  YOU, yashina(u) - rear, support, adopt

館  KAN - building, hall