3 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.
• 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.")

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?