Grammar - past perfect continuous tense
Past perfect continuous - use
We use the past perfect continuous when we talk about something that was happening until a moment in the past.

Past perfect continuous - form
We form the pas perfect continuous by past tense of 'to have': had + been + infinitive + ing
Voorbeelden:
- When they finally arrived, I had been waiting one hour.
Toen ze eindelijk arriveerden, had ik een uur lang gewacht.
- John had been taking quite a few driving lessons, but he gave up.
John heeft best een aardig aantal autorijlessen gehad, maar hij is gestopt.