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
If I had studied harder,	I would have passed the exam.

Explanation: 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:

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*
main clause	subject + would (OR could, OR might) have + 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:

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:

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.

Last week you bought a lottery ticket. But you did not win. :-(

	condition	result
	Past Perfect	WOULD HAVE + Past Participle
If	I had won the lottery	I would have bought a car.

IF	condition	result
	past perfect	WOULD HAVE + past participle
If	I had seen Mary	I would have told her.
If	Tara had been free yesterday	I would have invited her.
If	they had not passed their exam	their teacher would have been sad.
If	it had rained yesterday	would you have stayed at home?
If	it had rained yesterday	what would you have done?

result	IF	condition
WOULD HAVE + past participle		past perfect
I would have told Mary	if	I had seen her.
I would have invited Tara	if	she had been free yesterday.
Their teacher would have been sad	if	they had not passed their exam.
Would you have stayed at home	if	it had rained yesterday?
What would you have done	if	it had rained yesterday?

Example	Explanation
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 we had played a little better, we could have won the game.	Regret: We didn't play well, so we lost the game.
If you had saved your money, you could have bought a computer.	Criticism: You didn't save your money, so now you can't afford a computer.
If it had snowed, we could have gone skiing.	Regret: It didn't snow, so we couldn't go skiing.

Here are some examples traslate

If I had won the lottery, I would have traveled around the world.Si yo hubiera ganado la lotería, habría viajado por todo el mundo.

If I had seen him, I would have told him about you.Si lo hubiese visto, le habría contado acerca de ti.

If I had known the answer, I would have raised my hand.Si hubiese sabido la respuesta, habría levantado mi mano.

If she had come on Saturday, I would have seen her.Si ella hubiese venido el sábado, la habría visto.

If they had left earlier, they would have arrived on time.Si ellos hubiesen salido más temprano, habrían llegado a tiempo.

If we had studied harder, we might have passed the test.Si hubiésemos estudiado más duro, podríamos haber aprobado la prueba.

If you had gone to Brazil, you would have had lots of fun.Si tu hubieses ido a Brasil, habrías tenido mucha diversión.

If I hadn't been so busy, I could have helped you.Si no hubiese estado tan ocupado, te podría haber ayudado.

If you had phoned me, I would have known you were here.Si tu me hubieses telefoneado, habría sabido que estabas aquí.

If they had invited us, we would have accepted at once.Si ellos nos hubiesen invitado, habríamos aceptado de inmediato.

If she had explained me the problem, I would have understood it.Si ella me hubiese explicado el problema, lo habría entendido.

LETS PRACTICE :) ...

1. Complete the following sentences with the THIRD CONDITIONAL. Use abbreviations for the negative verbs:

  

a) If Jane  (not/lose) her job as a sales representative in London, she  (not/move) to Edinburgh.

b) If she  (not/move) to Edinburgh, she  (not/find) a job in a new company.

c) If she  (not/find) a job in the new company, she  (not/meet) Adam.

d) If she  (not/meet) Adam, they  (not/fall) in love.

e) If they  (not/fall) in love, Adam  (not/ask) Jane to marry him.

  

 f) If Michael's alarm clock  (ring) on time, he  (have) time to have breakfast at home.

g) If he  (have) breakfast and home, he  (feel) more relaxed.

h) If he  (feel) more relaxed, he  (not/drive) so fast.

i) If he  (drive) slowly, he  (see) the "STOP" sign.

j) If he  (see) the sign, he  (not/crash) against the other car.

2. Choose the correct ending for the following sentences:

a) If the weather had been better yesterday, we had gone to the countrysidewe'd have gone to the countrysidewe'd had gone to the countryside

b) If Jane had arrived on time last night, we would have watched a film togetherwe had watched a film togetherwe could watch a film together

c) If I had studied more for my exams, my grades would be bettermy grades would have been bettermy grades had been better

d) We would have had a wonderful weekend if it hadn't begun to rainif it hadn't began to rainif it wouldn't have begun to rain

e) The party would have been funnier if my parents hadn't decided to stayif my parents wouldn't have decided to stayif my parents would have decided to stay

Heres this video 

HERE YOU CAN PRACTICE MORE...  http://www.perfect-english-grammar.com/third-conditional-exercise-1.html

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