2029. What characters can be added here so that each character contains a part of the previous character? a) 切 -> _ -> _ -> 坊 b) 菓 -> _ -> _ -> 編

a) 切 -> 召 -> 吐 -> 坊  

切  SETSU, ki(ru), ki(reru) - cut

召  SHOU, me(su) - summon, wear, take

吐  TOU, ha(ku) - spew, vomit, give vent to

坊  BOU, BO - priest's residence, priest, boy

b) 菓 -> 柱 -> 素 -> 編  

菓  KA - cake, fruit

柱  CHUU, hashira - pillar, column, pole

素  SO, SU - element, naked, simple

編  HEN, a(mu) - knit, crochet, compile