aight lets say in Ab a song like jesus on the main line in the A section the bass would b (Ab,c,Db,d,Eb,f,Gb,g) and repeat till you go to the B section which would b the 4th note in the major scale of Ab which is Db (Db,f,b,Bb,Db,f,Ab,f,d,f,Ab,b,Eb,f,Gb,g) then back to the A section 1 time the the C section G,C,F,C,Db,D then the D section Eb,E,F,B,Bb,E,Eb,A,Ab then the turn around C,Db,D,Eb