2198. What characters can be added here so that each character contains a part of the previous character? a) 畑 -> _ -> _ -> 吹 b) 炎 -> _ -> _ -> 幸

a) 畑 -> 男 -> 加 -> 吹  

畑  hatake - cultivated field

男  DAN, NAN, otoko - male, man

加  KA, kuwa(eru), kuwa(waru) - add, append, join, take part

吹  SUI, fu(ku) - blow

b) 炎 -> 畑 -> 里 -> 幸  

炎  EN, honou - flame

畑  hatake - cultivated field

里  RI, sato - village

幸  KOU, shiawa(se), sachi - happiness, good fortune