654. What character can be added to both of these characters to give other characters? 苗_ -> _東

Answer:

苗  BYOU, nae, nawa - seedling, sapling

東  TOU, higashi - east

Add 木: 苗+木 木+東 

木  MOKU, BOKU, ki - tree

菓  KA - cake, fruit

棟  TOU, mune, muna - ridge of a roof