The third conditional is used to speculate about hypothetical situations in the past. It consists of two clauses: an "if" clause using "if + subject + past perfect" and a main clause using "subject + would/could/might have + past participle." For example, "If I had studied harder, I would have passed the exam." The third conditional expresses criticism or regret about things that did not actually happen in the past.

1. 3. Tercer condicional / Third Conditional
Indica una condición en el pasado, que ya no se puede cumplir.
IF + past perfect ...
+ conditional perfect (would have).
If I had learnt, I would have passed the exam.
If he had worked hard in all his subjects, he would not have failed this semester.
(Si él hubiera trabajado en todas sus asignaturas, él no hubiera suspendido este
semestre)
If we had been more careful, we wouldn't have had the accident.
(Si hubiésemos sido más cuidadosos, no habríamos tenido el accidente.)
Otros casos
Existen otras formas de construir frases condicionales:
IF + simple present, ... present simple
If you ring this number, nobody answers.
IF + simple present, ... imperativo.
If you drink, don't drive.
Third Conditional
We use the third conditional (also known as the "past unreal conditional") to talk about
situations in the past that didn’t happen and their hypothetical consequences.
The third conditional consists of two clauses.
One is formed with If + subject + past perfect verb ("If I had studied"). The second is
formed with subject + would have + past participle ("I would have passed the test").
So all together, the sentence looks like this: "If I had studied, I would have passed the
test."
In the past, I didn't study. But by using this type of conditional, I can speculate about
how things would have been different, if I had been a better student.
Third conditional
We can use the Third Conditional to talk about 'impossible' conditions, impossible because
they are in the past and we cannot change what has happened.
• If I had worked harder at school, I would have got
better grades.
• If I had had time, I would have gone to see him. But
I didn't have time.

2. • If we had bought that house, we would have had to
rebuild the kitchen.
• If we had caught the earlier train, we would have got
there on time but we were late.
Notice that the main clause can contain 'would', 'could' or 'might.
• If I had seen him at the meeting, I would have asked
him. (But he wasn't there so I didn't.)
• If I had seen him at the meeting, I could have asked
him. ( But he wasn't there so it wasn't possible.)
• If I had seen him at the meeting, I might have asked
him. (But I'm not sure. Perhaps if the opportunity
had arisen.)
• If I had paid more attention in class, I would have
understood the lesson.
Also notice that sometimes the 'if clause' is implied rather than spoken.
• I'd have done it. ("if you had asked me but you
didn't.")
• I wouldn't have said that. ("if I'd been there.")
• He wouldn't have let him get away with that. ("if he
had tried that with me.")
Te invitamos a que entres a esta página y desarrolles los siguiente ejercicios
http://www.englishgrammarsecrets.com/thirdconditional/exercise1.swf
Desarolla el siguiente ejercicio
The Third Conditional
1. He crashed his car, because he fell asleep while driving.
If he asleep while driving, he his car.
2. We couldn't go to the concert, because we didn't have enough money.
If we enough money, we to the concert.
3. I lost my job because I was late for work.
I my job if I late for work.
4. The wind was so strong that the bridge collapsed.
If the wind so strong, the bridge .
5. I couldn't call Sally because I had lost her number.
I Sally if I her number.

3. Third Conditional
Introduction
The third conditional (also called conditional type 3) is a structure used for talking
about unreal situations in the past. This page will explain how the third conditional is
formed, and when to use it.
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 explanation
If I had I would have
I failed the exam, because I
studied passed the
didn't study hard enough.
harder, exam.
If the "if" clause comes first, a comma is usually used. If the "if" clause comes
second, there is no need for a comma:
main clause if clause
I probably would have passed the exam if I had studied harder.
We use different verb forms in each part of a third conditional:
if clause if + subject + past perfect verb*

4. main subject + would (OR could, OR might) have +
clause past participle
*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:
If I had studied harder, I probably would
Full form have passed the exam.
Contracted If I'd studied harder, I probably would've
form 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:
Example Explanation
If you had driven more Criticism: You had an accident
carefully, you would not because you didn't drive
have had an accident. carefully enough.
If we had played a little Regret: We didn't play well, so
better, we could have won we lost the game.

5. the game.
If you had saved your Criticism: You didn't save your
money, you could have money, so now you can't afford
bought a computer. a computer.
If it had snowed, we could Regret: It didn't snow, so we
have gone skiing. couldn't go skiing.