Do you remember what is Present Perfect?
That was easy for you to learn.
Now we are going to study the Past Perfect vs Past Perfect Continuous.

The rules are the same as the rules of Present Perfect and Present Perfect Continuous, but we use them in the past tense.

• I have done -> I had done.
• I have been doing -> I had been doing.

We need Past Perfect and Past Perfect Continuous to stick to the rules of sequence of tenses:

• They were not at home. They did not know that she had already gone to the station.
• I didn’t have enough money. I had spent everything long time ago.
• We had a lot to think over. That conversation had made them change their mind.
• She was sorry. She had made a big mistake.
• Today he was happy without his friend. However, he had not created the mechanism alone.

The first part of the sentence is in the Past Simple/Present Perfect.

The second part of information tells us about the action that happened before the first one.

So we need to use the Past Perfect construction.

The same rule works for Past Perfect Continuous. We take the Past Perfect construction for “have”, and “be,” and we add the Continuous form of the main verb.

• He was ready to drop; he had been running.
• She had been watching a horror film for 15 minutes when someone touched her shoulder.
• When we came out, we saw a lot of puddles. It had been raining. (That’s my favorite example from every textbook I ever had.)

Please, pay attention to the Past Perfect Continuous tense.

We use this tense to tell about some continuous action that was happening before we made another action. We can’t describe a simultaneous action; in that case, we will use the Past Continuous tense.

Once again, the Perfect tense gives a suggestion that something happened before our interference and that we have the result of that previous action up to the moment of speaking.