Third Conditional – Fake Past
The third conditional is not used as frequently as the others, but it is still a good one to know. In this case we are talking about an unreal past (something in the past that didn’t happen) and the result of that condition.
“If I hadn’t drunk so much last night I wouldn’t have had a hangover this morning.”
We use past perfect for the condition (“If + had + participle”) since we are talking about a completed event in the past that doesn’t affect the present. In the main clause we have our modal (would, wouldn’t, might, may…)+ have + past participle.
Wow, I know this one sounds complicated. Just think of it as two fake stories in the past.
“If I hadn’t drank so much last night…”
Fake past, didn’t happen. I actually drank a lot.
“I wouldn’t have had a hangover this morning”
Fake past, didn’t happen. I did have a hangover.
The third conditional is often used to express regret :
“If I hadn’t drank so much last night I wouldn’t have lost my phone”
or to admonish others
“If you had studied for the test you wouldn’t have failed.”