For each of the following molecules or ions of sulfur and oxygen, write a single Lewis structure

Question:

For each of the following molecules or ions of sulfur and oxygen, write a single Lewis structure that obeys the octet rule, and calculate the oxidation numbers and formal charges on all the atoms:
(a) SO2,
(b) SO3,
(c) SO32-
(d) Arrange these molecules / ions in order of increasing S-O bond distance.