Answer:
D. -2, -4, -6, -8, -10, -12
rule: subtracted by 2
F. 20, 16, 12, 8, 4, 0, -4
rule: subtracted by 4
G. 2, 5, 8, 11, 14, 17, 20
rule: added by 3
H. 7/7, 9/7, 11/7, 13/7, 15/7, 17/7
rule: added by 2/7
I. 3, 9, 27, 81, 243, 729
rule: multiplied by 3