That's the easy question, though we'll have a couple of centuries to think it over.

That'd be scientists going back into the last couple of centuries.

It's changed a lot in the couple of centuries I've been coming back to it.

It could go on that way for another couple of centuries.

It could just as well have been a couple of centuries.

I got around to it a couple of centuries later.

So, give or take a couple of centuries and a few hundred light years, I'm home.

We haven't made very many friends in the past couple of centuries.

It wasn't very good to begin with, and it's been there for at least a couple of centuries.

So you're good for a couple of centuries without trying.