Would

[nouamaneer]

Still not covinced! Sorry. But thank you anyway ;)

[5jj]

Still not covinced! Sorry. But thank you anyway ;)

If we use a 'historic present' we can write:1815. Napoleon arrives on St Helena. He will never see see France again.

Looking back on this, we can write: In 1815 Napoleon arrived on St Helena. He would never see France again.

There are other ways of expressing this idea, but would is normal and natural.

[Raymott]

Our original problem is with a sentence I found in one od Oxford's Advenced level coursebooks, namely 'Solutions Advanced'.

It says that the following sentence is ungrammatical:

* My parents would llive in a cottage in the country before they moved to the city center.

Possibilties of correction are: 1- Used to. 2- Lived. 3- Were living.

But my dilemma is in finding an argument to rule out 'Would' in that context. Why????

Yes, in general, that sentence is wrong. You could (as others have) make a context for the sentence in the past-in-the-future. It's not a good candidate sentence for that though, and needs to be added to.
As it stands, the sentence is ungrammatical. The point that the grammar book is making (and you must understand that grammar books are there to make points) is that you use "used to", etc. in all cases that read vaguely like this, unless you have a very good reason to do otherwise.
The best argument against it is that we (English speakers) don't use it in that context.

What exactly is it that you are not convinced about?