Perfect conditional

It is used in the 3rd Conditional to talk about imaginary situations in the past: eg: If she'd seen the advert, she would have applied for the job.
NOTE: 'If she'd seen = If she had seen

Formation:

• 'WOULD HAVE' + Past Participle

Perfect conditional - form
The perfect conditional of any verb is composed of two elements: would + the perfect infinitive of the main verb (=have + past participle):

Subject	would	perfect infinitive
He They	would would	have gone... have stayed...
Affirmative
I	would	have believed ...
Negative
She	wouldn't	have given...
Interrogative
Would	you	have left...?
Interrogative negative
Wouldn't	he	have been...?

Example: to go, Past conditional

Affirmative	Negative	Interrogative
I would have gone	I wouldn't have gone	Would I have gone?
You would have gone	You wouldn't have gone	Would you have gone?
He would have gone	She wouldn't have gone	Would it have gone?
We would have gone	We wouldn't have gone	Would we have gone?
You would have gone	You wouldn't have gone	Would you have gone?
They would have gone	They wouldn't have gone	Would they have gone?

In these sentences, the time is past, and the situation is contrary to reality. The facts they are based on are the opposite of what is expressed.
Type 3 conditional sentences, are truly hypothetical or unreal, because it is now too late for the condition or its result to exist. There is always an unspoken "but..." phrase:

• If I had worked harder I would have passed the exam
  (but I didn't work hard, and I didn't pass the exam).
• If I'd known you were coming I'd have baked a cake
  (but I didn't know, and I haven't baked a cake).

NOTE: Both would and had can be contracted to 'd, which can be confusing. Remember that you NEVER use would in the IF-clause, so in the example above, "If I'd known" must be "If I had known", and "I'd have baked" must be "I would have baked.."

Subject + Would + Have + Past participle of the verb.

	know	eat
I	would have known	would have eaten
You	would have known	would have eaten
He/She/It	would have known	would have eaten
We	would have known	would have eaten
They	would have known	would have eaten