Possession problem

[Anhminh1232002]

Can I write:
The problems of the poor.
The poor's problems.

The top of the page.
The page's top.

The roof of the house.
The house's roof.

The government's decision.
The decision of the government.

The earth's gravity.
The gravity of the earth.

Which ones are correct? Thanks.

[Dozy]

The versions with "of" are all correct, though I would prefer to capitalise "Earth". Regarding the others, in my opinion:

"the government's decision" and "the Earth's gravity" are OK.

"the poor's problems", "the page's top" and "the house's roof" are not impossible but are more awkward.