PAST PERFECT SIMPLE

Past Perfect
FORM
[had + past participle]

Examples:

You had studied English before you moved to New York.
Had you studied English before you moved to New York?
You had not studied English before you moved to New York.

USE 1 Completed Action Before Something in the Past


The Past Perfect expresses the idea that something occurred before another action in the past. It can also show that something happened before a specific time in the past.

Examples:

I had never seen such a beautiful beach before I went to Kauai.
I did not have any money because I had lost my wallet.
Tony knew Istanbul so well because he had visited the city several times.

Do the following exercises:
http://www.englisch-hilfen.de/en/exercises/past_perfect_simple_past1.htm
http://www.ego4u.com/en/cram-up/grammar/past-perfect-simple/exercises
http://www.english-zone.com/verbs/pstperf1.html
http://www.learnenglish.org.uk/words/activities/pastperf02.html