The construction of The Past Perfect Tense :
had + worked
The past perfect tense denotes a completed past activity which happened before another past action or point of time we have in mind.
Examples
They have left before we came.
When they reached the station, the train had already left.
He had gone long before the letter came.
We had just sat down to dinner when phone start to rang.
I had not have money before I start to work.
