a) 架 -> 柱 -> 素 -> 終
架 KA, ka(keru), ka(karu) - hang, build (a bridge)
柱 CHUU, hashira - pillar, column, pole
素 SO, SU - element, naked, simple
終 SHUU, o(waru), o(eru) - end, finish
b) 吉 -> 吐 -> 埋 -> 黒
吉 KICHI, KITSU, yoshi - good luck
吐 TOU, ha(ku) - spew, vomit, give vent to
埋 MAI, u(maru), u(meru), u(moreru) - bury, be buried, filled up
黒 The "Kuro" radical - black