Quick Overview of the Third Conditional

The third conditional is used to talk about unreal or hypothetical situations in the past—things that didn’t happen but could have. It’s often used to express regret or imagine different outcomes.

In an affirmative (positive) third conditional sentence, the structure is:

• If + past perfect, would have + past participle

For example:

“If I had known about the meeting, I would have attended.”

This sentence imagines a past situation that didn’t actually happen: I didn’t know about the meeting, so I didn’t attend.

Forming the Negative Third Conditional

To form the third conditional in the negative, simply make the “would have” part negative. Instead of saying “would have,” we say “would not have” (or wouldn’t have for short).

Negative Third Conditional Structure:

• If + past perfect, wouldn’t have + past participle

Example:

“If she had studied, she wouldn’t have failed the test.”

This means she didn’t study, and as a result, she failed.

More Examples of Negative Third Conditional Sentences

Here are a few more examples to clarify how this works:

1. If we had left earlier, we wouldn’t have missed the flight.
   • (We didn’t leave earlier, so we missed the flight.)
2. If he had saved his money, he wouldn’t have struggled financially.
   • (He didn’t save his money, so he struggled financially.)
3. If I had listened to you, I wouldn’t have made that mistake.
   • (I didn’t listen to you, so I made the mistake.)

Practice Exercise

Try completing these sentences using the negative third conditional structure:

1. If I had set an alarm, I __________ (miss) the appointment.
2. If they had known about the traffic, they __________ (arrive) late.
3. If she had taken the medicine, her condition __________ (worsen).

Answers:

1. wouldn’t have missed
2. wouldn’t have arrived
3. wouldn’t have worsened