Conditionals are sentences with two clauses – an “if” clause and a main clause – that are closely related. There are three different conditional clauses.
- 3rd conditional: We use the third conditional to describe the past. It describes something that didn't happen.
If I had studied harder, I would have gone to university → He didn't study hard so he didn't go to university.
We make the third conditional with:
If clause (past participle)
Main clause (would + present perfect)
|If he had gone to university||
he would have had a better job
It's not important what clause goes first. The order of the clauses can be changed.
When making questions, the order of some of the words change like they do in ordinary questions:
What would you have told him if you had arrived on time?
Would you have accepted the job if they had offered it to you?
Notice that the subject in questions goes between “would” and the “have”.