We use the 3rd Conditional to speak hypothetically about things that didn’t happen in the past. It is how we talk about what we image the results would have been. We use it to speculate, but we also often use it for wishes and regrets and to make excuses.
Here is the structure:

Contractions:
You can contract Subject + would + have in two different ways. See the chart for how you can do it:
Subject + would + have
I would have
you would have
he would have
she would have
it would have
we would have
they would have
To contract subject + would
I’d have
you’d have
he’d have
she’d have
it’d have
we’d have
they’d have
To contract would + have
I would’ve
you would’ve
he would’ve
she would’ve
it would’ve
we would’ve
they would’ve
Speculate as to what might have happened in the following situations:
What would have happened…
if you had grown up in a different country?
If you hadn’t met your partner (or ex)?
if you had gone into a different profession?
if you had had the opportunity to study anything you wanted at school?
if you had been born the opposite sex?
if you had been born a genious?
