How do we use the Past Perfect Tense?

The Past Perfect tense expresses action in the past before another action in the past. This is the past in the past. For example:

The train had left when we arrived.
past present future
Train leaves in past at 9:00    
9:00 9:15  
We arrive in past at 9:15    

Look at some more examples:

You can sometimes think of the Past Perfect tense like the Present Perfect tense, but instead of the time being now the time is before.

  past present future

For example, imagine that you arrive at the station at 9:15am. The stationmaster says to you:

Later, you tell your friends:

We often use the Past Perfect in reported speech after verbs like: said, told, asked, thought, wondered

Look at these examples: