Present and Past Unreal Conditionals

Unreal conditionals are used to talk about situations that are improbable, imaginary, or past events that never occurred.

Second conditional is used to talk about situations in the future that have a probable or improbable chance of happening (10% chance).  For example if I say: If I would go to Rome, I could have an audience with the Pope.  There is a probability that I could go to Rome, but an audience with the Pope is highly improbable, but not impossible, it could happen.

Second Conditional

Format

	Condition	Result clause
	past conditional	would + base form of the verb
If	I went to Rome	I would have an audience with the Pope.
If	I had a million dollar salary	I would buy a Mansion in New York.

You can also start with the result clause

Result clause		Condition
would + base form of the verb		past conditional
I would have an audience with the Pope.	If	I went to Rome
I would buy a Mansion in New York.	If	I had a million dollar salary

Third conditional is used to talk about situations in the past that have 0% probability of happening, because they depend on a condition in the past changing and that can't happen.


Third Conditional

Format

	Condition	Result clause
	past perfect	would + past participle
If	I had gone to Rome	I would have had an audience with the Pope.
If	I had had a million dollar salary	I would have bought a Mansion in New York.

or 

Result clause		Condition
would + past participle		past perfect
I would have had an audience with the Pope.	If	I had gone to Rome
I would have bought a Mansion in New York.	If	I had had a million dollar salary

Conditionals-English Club