2231. What characters can be added here so that each character contains a part of the previous character? a) 早 -> _ -> _ -> 含 b) 針 -> _ -> _ -> 坪

a) 早 -> 古 -> 吟 -> 含  

早  SOU, SA, haya(i) , haya(meru) - early, fast, hasten

古  KO, furu(i) - old

吟  GIN - sing, chant, recite

含  GAN, fuku(mu), fuku(meru) - hold, include, contain

b) 針 -> 古 -> 吐 -> 坪  

針  SHIN, hari - needle

古  KO, furu(i) - old

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

坪  tsubo - unit of area