You can also form questions in the third conditional. The structure is:

If + subject + past perfect, would + subject + have + past participle?

If you had called me, would I have been able to help?

If he had asked for directions, would he have found the place?

You can make it negative by adding not after would (wouldn't have) or by using the negative form of had (hadn't).

If I had known, I wouldn't have gone to the party.

If they hadn't missed the bus, they would have been on time.

If + past perfect, ... would have + past participle.

If (past perfect) → the condition (something that did not happen in the past)

would have + past participle → the result (what would have happened if the condition had been true)

Example sentences:

If I had studied harder, I would have passed the exam.

(But I didn’t study harder, and I didn’t pass the exam.)

If they had left earlier, they would have caught the train.

(But they didn’t leave earlier, and they missed the train.)

If she had known about the meeting, she would have attended.

(But she didn’t know, and she didn’t attend.)

1. If I __________ (study) harder, I __________ (pass) the test.

2. If they __________ (leave) earlier, they __________ (catch) the train.

3. If we __________ (know) about the party, we __________ (go).

4. If she __________ (ask) for help, she __________ (understand) the lesson better.

5. If he __________ (not break) his leg, he __________ (play) in the match.

1. If you had told me, I __would have

   ________ (would have/would) helped you.

2. If they hadn’t been late, they ___wouldn’t have_______ (would have/would) missed the beginning of the movie.

3. If I ___had_______ (had/have) known it was your birthday, I __would have________ (would have/would) bought a gift.

4. If he ___hadn’t_______ (hadn't/had) eaten so much, he __would have________ (would have/would) felt better.

5. If we __hadn’t________ (hadn't/had) left so late, we _____would have_____ (would have/would) arrived on time.

1. If they __________ (not leave) early, they __________ (not catch) the flight.

2. If I __________ (not forget) to bring my umbrella, I __________ (not get) wet.

3. If we __________ (not make) the wrong turn, we __________ (not get) lost.

4. If she __________ (not lose) her keys, she __________ (not be) locked out of the house.

5. If he __________ (not lose) his wallet, he __________ (not have) to borrow money.

1. If you __________ (study) more, __________ (you/pass) the exam?

2. If I __________ (invite) you to the concert, __________ (you/come)?

3. If they __________ (arrive) earlier, __________ (they/not/miss) the presentation?

4. If we __________ (take) a taxi, __________ (we/get) there faster?

5. If she __________ (know) about the problem, __________ (she/help)?

Exercise 1:

1. had studied / would have passed

2. had left / would have caught

3. had known / would have gone

4. had asked / would have understood

5. hadn't broken / would have played

Exercise 2:

1. would have

2. would have

3. had / would have

4. hadn't / would have

5. hadn't / would have

Exercise 3:

1. hadn't left / wouldn't have caught

2. hadn't forgotten / wouldn't have gotten

3. hadn't made / wouldn't have gotten

4. hadn't lost / wouldn't have been

5. hadn't lost / wouldn't have had

Exercise 4:

1. had studied / would you have passed?

2. had invited / would you have come?

3. had arrived / would they not have missed?

4. had taken / would we have gotten?

5. had known / would she have helped?