The past perfect tense of verbs, simple and continuous, are formed as follows:

Past Perfect Simple
AFFIRMATIVE	NEGATIVE		INTERROGATIVE
	Long Form	Contracted Form
I had done	I had not done	I hadn't done	Had I done?
You had done	You had not done	You hadn't done	Had you done?
He/she/it had done	He/she/it had not done	He/she/it hadn't done	Had he/she/it done?
We had done	We had not done	We hadn't done	Had we done ?
You had done	You had not done	You hadn't done	Had you done?
They had done	They had not done	They hadn't done	Had they done?

Past Perfect Continuous
AFFIRMATIVE	NEGATIVE		INTERROGATIVE
	Long Form	Contracted Form
I had been doing	I had not been doing	I hadn't been doing	Had I been doing?
You had been doing	You had not been doing	You hadn't been doing	Had you been doing?
He/she/it had been doing	He/she/it had not been doing	He/she/it hadn't been doing	Had he/she/it been doing?
We had been doing	We had not been doing	We hadn't been doing	Had we been doing ?
You had been doing	You had not been doing	You hadn't been doing	Had you been doing?
They had been doing	They had not been doing	They hadn't been doing	Had they been doing?

• • The past perfect simple is used to refer to finished actions or completed events which took place before a specific time in the past.
    
    
    • Yesterday, between 4pm and 6pm, Paul played a game of tennis with Tom.
      His mother arrived at 6 pm. The game was over.
      When his mother arrived, Paul had finished the game.
      
      
    • When Tom got to the station the train had already left.
      
      
    • The boy was cold because he had forgotten his jacket.
      
      
    • Laura had visited Tokyo several times before she went to work there.

• The past perfect continuous is used to refer to a past continuous action, an action that was in progress up to a particular time in the past.
  
  
  • Before his mother arrived, Paul had been playing tennis with Tom.
    
    
  • I had been searching for a long time before I found the book under the sofa.
    
    
  • Eva was tired at lunch-time because she had been cleaning the house all morning.
    
    
  • Bill had been working in the company for 6 months before he met the boss.