2210. Read that back to me! What do these characters have in common? 居 各 押 胃 哀

They all have a reading that is the same backwards.  

居  KYO, i(ru) - be, exist

各  KAKU, onoono - each, every, various

押  OU, o(su), o(saeru) - push, suppress

胃  I - stomach

哀  AI, awa(re), awa(remu) - sorｒowful, pity, sympathise