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Third conditional – Grammar Chart

Third conditional – past unreal situations

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If clause and main clause

We use the past perfect in the if-clause of a third conditional sentence to talk about an imaginary or hypothetical situation in the past, and we use would have, could have or might have + past participle in the main clause to talk about the result or consequence of that imaginary situation.

  • If you had come to class more often, you would have passed the test.
  • If he hadn’t taken his helmet, he could have died.
  • If the jacket had been a bit cheaper, I might have bought it.


As with all conditional types, we use a comma after the ifclause when it goes at the beginning of the sentence, but we don’t use a comma when the if-clause goes at the end.

  • If I hadn’t overslept, I wouldn’t have been late.
  • I wouldn’t have been late if I hadn’t overslept.


We can also use unless in conditional sentences to mean if … (not)

  • I wouldn’t have arrived on time unless I had taken a taxi.
  • = I wouldn’t have arrived on time if I hadn’t taken a taxi.