The third conditional (also called conditional type 3) is a structure used for talking about unreal situations in the past.
→ The important thing about the third conditional is that both the condition and result are impossible now.
How the third conditional is formed, and when to use it.
We use different verb forms in each part of a third conditional:
The structure of a third conditional sentence
Like the other conditionals, a third conditional sentence consists of two clauses, an "if" clause and a main clause:
if clause +main clause
Ex. If I had studied harder, I would have passed the exam.
I failed the exam, because I didn't study hard enough.
If the "if" clause comes first, a comma is usually used. If the "if" clause comes second, there is no need for a comma:
Ex. probably would have passed the exam if I had studied harder.
Ex.We would have come yesterday if we had known about it.
If I had waited longer last night, I might have found out about it.
- If I had gone to the supermarket I could have bought some bread.
*The past perfect is formed with the auxiliary verb "had", and the past participle (or third form) of the verb.
Note also that third conditional forms can be contracted:
Full form: If I had studied harder, I probably would have passed the exam.
Contracted form: If I'd studied harder, I probably would've passed the exam.
Using the third conditional
The third conditional is used to talk about things which DID NOT HAPPEN in the past. If your native language does not have a similar construction, you may find this a little strange, but it can be very useful. It is often used to express criticism or regret.
If you had driven more carefully, you would not have had an accident.
(Criticism: You had an accident because you didn't drive carefully enough. )
If it had snowed, we could have gone skiing.
(Regret: It didn't snow, so we...