B2 · Lesson 23 · 25 min
Third conditional and past alternatives
In this lesson
- I can imagine a different condition and result in the completed past.
- I can distinguish a hypothetical past result from the events that actually happened.
Grammar in context
Dina missed the early train because she left home late. If she had left ten minutes earlier, she would have caught it. If she had caught it, she could have attended the whole workshop.
Did Dina leave earlier or catch the train? Which form imagines a past result rather than describing a real one?
Imagine an unreal alternative to the past
The third conditional commonly uses if plus past perfect and would have plus a past participle. Both the condition and result concern a completed past situation that the speaker presents as unreal. In if I had booked, I would have saved money, the speaker normally implies that the booking did not happen as imagined. Explain the actual situation when necessary, especially if a negative condition could make the relationship hard to follow.
- If we had checked the address, we would have found the office.
- If the shop had been open, I would have bought a charger.
Form each clause separately
The if-clause needs had plus a past participle. The result clause needs would have plus a past participle, with not after had or would for negatives. Either clause can come first; use a comma when the if-clause comes first. In standard examples of this pattern, do not put would have inside the if-clause. Contracted ’d may stand for had or would, so use the following verb form to identify its role.
- If she had not called, we would not have known.
- We would have waited if we had seen your message.
Allow possible results as well as expected ones
Could have and might have can replace would have when the intended result is an ability, opportunity or possibility rather than the speaker’s expected outcome. These choices do not make the condition real. Keep the time reference in the past and preserve the strength of the original claim. A missed possibility is different from a guaranteed outcome, so a careful speaker does not automatically replace might with would when paraphrasing.
- If I had brought my laptop, I could have shown you the files.
- If the weather had improved, we might have stayed longer.
Common mistakes
Compare the incorrect and corrected forms.
Avoid
If I would have known, I would have helped.
Use
If I had known, I would have helped.
The standard third-conditional if-clause uses past perfect.
Avoid
She would have took the train.
Use
She would have taken the train.
Would have needs the past participle taken.
Put it into practice
Try the exercises, write your own examples and check your understanding.