2.
1) of, 2) the, 3) had, 4) be, 5) many, 6) were, 7) it, 8) last, 9) too
3.
1) These are his shoes. These shoes are his.
2) This will be their flat. This flat will be theirs.
3) This isn't our computer. This computer isn't ours.
4) These are my books. These books are mine.
5) These are his or her books. These books are either his or hers.