We make the third conditional by using the past perfect after 'if' and then 'would have' and the past participle in the second part of the sentence:
- if + past perfect, ...would + have + past participle
It talks about the past. It's used to describe a situation that didn't happen, and to imagine the result of this situation.
- If she had studied, she would have passed the exam (but, really we know she didn't study and so she didn't pass)
- If I hadn't eaten so much, I wouldn't have felt sick (but I did eat a lot, and so I did feel sick).
- If we had taken a taxi, we wouldn't have missed the plane
- She wouldn't have been tired if she had gone to bed earlier
- She would have become a teacher if she had gone to university
- He would have been on time for the interview if he had left the house at nine
Click here for an exercise about making the third conditional.
Click here for all the conditional exercises.