Grammar(Past perfect tense)

The past perfect tense is used to show an action that was completed in the past before another action. It is formed by adding (had) to the past participle. Examples are:

1. I (had slept) before she (came).
   [The sleeping occurred before her coming].
2. I (had gone) to the kitchen when the telephone (rang). [Going to the kitchen occurred before the ringing of the telephone.]
3. She (had worked) hard before she (wrote) the examination. [Working hard occurred before the writing of the examination.]