What you'll learn
By the end of this lesson, you'll be able to talk about unreal past situations: what would have happened if something had been different.
When do I use it?
Use the third conditional for unreal situations in the past — things that did NOT happen, and the consequences that would have followed:
- "If I had studied, I would have passed the exam." (I didn't study, and I didn't pass)
- "She would have called if she had known."
Both parts are unreal: the condition (if + had done) and the result (would have done).
How do I form it?
if + past perfect, would have + past participle would have + past participle + if + past perfect
- If we had left earlier, we wouldn't have missed the train.
- He would have bought the house if he had had the money.
- If you had told me, I would have helped you.
- They would have come if they had been invited.
The order can be reversed. Note "had had" (past of have) in "if he had had the money".
Common mistakes for Spanish speakers
Spanish speakers often keep the past simple or "si hubiera" → "would have" in the if-clause: "If I would have studied" is wrong — the if-clause takes "had + participle", never "would". Also "hubiera sido" is sometimes translated as "had been", but the result clause needs "would have been": "habría sido mejor" = "it would have been better", not "it had been better". Use would only in the result clause.
if + had done (condition) → would have done (result). Never "would" in the if-clause.
Practice
Multiple Choice
B2Which sentence is correct?
Fill in the Blank
B2If she had studied, she have passed the test.
Hint: The result clause uses would have + participle.
Find the Error
B2Sentence Transformation
B2Task: Rewrite as a third conditional
Hint: Unreal past: if + had done, would(n't) have done.
Practice Speaking
Apply what you've learned in a real conversation with AI feedback.
Level: B2