The unreal conditional

1. The Unreal Conditional is used when referring to unreal, imaginary or impossible conditions and their results. Both- If Clause and Result Clause, present the unreal result of the condition.

Example:

  If I lived in  palace , I would give parties all the time.

( But I don´t live in a palace, so I don´t give parties.)

· If I had a car , I would drive everywhere.

2. The verb in the If Clause is shown in simple past tense. In the Result Clause the auxiliary Would + base form of the verb is used.

Example:

  If Luisa went to Cusco , she would spend a great time

Note: 

a. The If Clause uses the simple past tense, but the meaning does not refer to the past.

· If I had money now, I would supply many things to myself.

b. Do not use the auxiliary Would in the If Clause in present unreal conditional sentences.

· If I bought some flowers to Mary, she would be happy.

NOT: If I would buy .......

c. Use Were for all people when the verb in the If Clause is in the basic form (be).

· If I were a king, I would contribute in many charity associations in all the world.

In American informal speech, you will sometimes hear Was used in the If Clause. However in formal speech it is wrong.

3. If the Result Clause is not quite true, then use Might or Could in the Result Clause to express possibility. You can also use Could in the Result Clause when expressing ability.

Example:

· If I had enough time, I could take dancing classes.

(It´s possible I would take dancing classes).

· If you spoke German, you could translate this letter for me.

4. Remember that you can vary the position of the sentences as this does not alter the idea. Note the use of commas.

· If I won the lottery, I would travel around the whole world.

· I would travel around the whole world if I won the lottery.

5. It is possible to convert one or both sentences into a negative form.

· If I caught a fish, I would share it with my partner.

· If I didn't catch a fish, I wouldn't share it with my partner.

· If I caught a fish, I wouldn´t eat it alone.

· If I didn´t catch a fsih , I would be happy.

6. Sentences beginning with If I were you, ... are often used to give advice.

· If I were you, I would wear that wonderful dress.

Second conditional

The second conditional already enters the field of hypothetical imaginary scenarios. It is used to raise unrealistic ideas of the present or actions in the future that are unlikely.

Grammatical structure of the second conditional

Option 1: If + Condition (sentence with a conjugated verb in the simple past) + would + Result (sentence with a verb in the infinitive).

Option 2: Result (sentence with verb in infinitive) + would + if + Condition (sentence with verb conjugated in past simple).

For example:

If I won the lottery, I would buy a house (If I won the lottery, I would buy a house).

You would speak Japanese if you lived in Japan (You would speak Japanese if you lived in Japan).

Third Conditional 

Also -Type III- Refers to a hypothetical situation in the past and is formed according to the structure: if + past perfect + conditional perfect.

Example:

If clause Main clause

If + Past Perfect tense would/could/might + have + past participle

If I had won the lottery, I would have traveled around the world.

Si yo hubiera ganado la lotería, habría viajado por todo el mundo.

If I had seen him, I would have told him about you.

Si lo hubiese visto, le habría contado acerca de ti.

If I had known the answer, I would have raised my hand.

Si hubiese sabido la respuesta, habría levantado mi mano.

If she had come on Saturday, I would have seen her.

Si ella hubiese venido el sábado, la habría visto.

If they had left earlier, they would have arrived on time.

Si ellos hubiesen salido más temprano, habrían llegado a tiempo.

If we had studied harder, we might have passed the test.

Si hubiésemos estudiado más duro, podríamos haber aprobado la prueba.

If you had gone to Brazil, you would have had lots of fun.

Si tu hubieses ido a Brasil, habrías tenido mucha diversión.

If I hadn't been so busy, I could have helped you.

Si no hubiese estado tan ocupado, te podría haber ayudado.

Exercise

Link: https://test-english.com/grammar-points/b1-b2/second-third-conditionals/