The pattern of the Third Conditional is as follows:
If + (Past Perfect Tense), would have + (Past Participle)
1. We use the Third Conditional when we talk about impossible conditions that they were happened in the past and we cannot change the result.
1a. If he had won the lottery yesterday, he would have bought a car.
1b. He would have bought a car if he had won the lottery yesterday.
2a. If it had rained yesterday, I would have stayed at home.
2b. I would have stayed at home if it had rained yesterday.
3a. If I had seen Sarah, I would have told her the secret.
3b. I would have told her the secret if I had seen Sarah.
4a. If I had studied harder, I would have passed the exam.
4b. I would have passed the exam if I had studied harder.
5a. If Jeffrey had had time yesterday, he would have gone to see her.
5b. Jeffrey would have gone to see her if he had had time yesterday.
Conditional Clause http://goo.gl/B0N4sb
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