When do we use the 3rd conditional?
The third conditional: if ... had done x
I didn't pass the exam. But if I had passed it, I would have registered for the civil engineering course at Nottingham Trent university. We didn't manage to get there by nightfall. But if we had (managed to get there), we would have slept in a comfortable bed and not on the ground.
I received some really excellent training for this job.
- Had I not been trained in this way, I wouldn't have survived in the job for very long.
- When my car broke down, I had to run very fast all the way to the station.
- If I hadn't run so fast, I would surely have missed the train.
The third conditional: if had(n't) been -ing
You were driving so fast.
If you hadn't been driving so fast, the accident would never have happened.
If you hadn't been looking out of the window at that moment, you wouldn't have witnessed the crime.
would've / might'veNote that if we want to introduce the idea of possibility into our assertion in the main clause, might've done can be used as an alternative to would've done:
If you hadn't been looking out the window just then, you might not have seen the crime being committed.
It's a pity you weren't wearing your glasses. If you had been wearing them, you might've noticed that it was a bull, not a cow, that was charging towards us.
would've / could've
- I am an adopted and unhappy child.
I often think that If my real mother had kept me, I could've danced in the street to earn money for us both.
- My dancing feet would have softened the hearts of the passers-by and they would've thrown money into the hat in front of us.
IF Condition + past perfect Result Would have + past participle
- If I had known, I would have helped.
I didn't know and didn't help. I'm sure I would have helped
- If I had known, I could have helped.
Although this didn't happen, the result is only a possibility.
- If I had known, I might have helped.
Although this didn't happen, the result is only a possibility
- If you had known, you should have helped.
Although this didn't happen, it is only a good suggestion or piece of advice.
The condition with no possibility
The first conditional and second conditionals talk about the future. With the third conditional we talk about the past. We talk about a condition in the past that did not happen. That is why there is no possibility for this condition. The third conditional is also like a dream, but with no possibility of the dream coming true.
In formal English, 'If I had known...' becomes 'Had I known...'