We use the past perfect simple to talk about what happened before a point in the past. It looks back from a point in the past to further in the past.
- I hadn’t known the bad news when I spoke to him.
- I checked with the supplier and they still hadn’t received the contract.
- She had already told him before I got a chance to give him my version.
- The company has started the year well but was badly hit by the postal strike.
The past perfect simple is often used when we report what people had said/thought/believed.
- He told me they had already paid the bill.
- He said he believed that John had moved to Italy.
- I thought we had already decided on a name for this product.
We use the past perfect continuous to look back at a situation in progress.
- It looked like a good time to invest. Inflation had been falling for several months.
- Before I changed jobs, I had been working on a plan to reduce production costs.
- We had been thinking about doing that but then decided against it.