In the series first ,third and fifth words are reversed to get second fourth and 6th words . Now let us observe the relation between First third and fifth sets of elements . G's position in alphabetical series is 7 , N's position is 14 . I's position is 9 and R's position is 18, K's position is 11 and V's position is 22 . First letters are getting incremented by 2 in the first second and third series . Next letters position is doubled . Using the same logic M must come as next sets first letter since its position is 13 and doubled positioned letter is Z . Hence we will get M and Z , Z and M as next elements .