We can use the third conditional to express an imagined situation in the past that didn’t actually exist or happen.
So, it is often used to express regret.
If + past perfect, would + have + past participle
_ If I had planned the trip better, we would have had a better time.
_ If I had known you were going, I would have gone too
When speaking, we can make the contraction in both clauses –
where in the first clause had becomes ‘d
and in the second clause would have becomes would’ve
_ If I’d planned the trip better, we would’ve had a better time.
Negatives can also be used in either clause.
_ If I’d planned the trip better, we wouldn’t’ve had such a bad time.
Part 2 Questions
We can use this tense to express regrets, especially when things didn’t go as planned or where the outcome was not good.
Examples could be
_ Bad service in a restaurant
_ A boring event
_ A delay
_ Missing a flight/train
_ A failed project / business
_ A time you were angry / someone lied
A:
If I had known the service
was going to be so bad,
I would’ve gone
somewhere else
A:
If I had known it was going to be
such a boring party,
I wouldn’t have gone
Possible substitutes for boring:
tedious / tiresome / dull
A:
If I had known the flight
was going to be delayed,
I would’ve gone
by train instead
Possible substitutes for delayed:
postponed / put back / cancelled
A:
If we had left on time,
we would’ve made the flight
A:
If he had worked harder,
he would’ve been more successful
A:
If she hadn’t forgotten my birthday,
I wouldn’t have got so angry
Possible substitutes for angry:
irritated / annoyed / upset