What are the SIGNAL WORDS that go with this tense? 

Before, after, when, by the time, for, since etc 

Do we use the past perfect for situations and states before the past?

Is the past perfect the past of the past?

Had you had your last computer for a long time before it stopped working?

Had you been living in you last house for long before you moved?

Do we use the past perfect for completed actions before a moment in the past?

When you got your last job, how long had you been unemployed? 

When you were born, how long had your parents been married?

Do we use the past perfect for series of actions continuing up to a moment in the past?

By the time Stephen Hawkins died, how many discoveries had he made? 

By the time you finished your education, how many places had you studied in?

Do we use the past perfect for completed action where the important thing is the result at a moment in the past?

Are you surprised that I won my last tennis match because I had practiced a lot with my coach?

What do you think my very first paella was like considering I had never made it before?