In Past Perfect Continuous Tense, we use had been with all the nouns or pronouns plus since/for with the time. Since for the point of time and For for the period of time.
- He had been doing this since last four years.
- She had been making noises for 10 minutes.
- It had been neighing since morning.
- I had been laughing for an hour.
- We had been studying since last 20 years.
- They had been doing that business for 10 months.
- You had been cheating on me since last 2 days.
- Eza had been making the clothes for months.
- The politicians had been befooling us for ages.
- I had been suffering from illness since this evening.
- They had been driving the car for 1 hour.
- We had been developing this page since the last four weeks.
- He had been taking selfies for 2 hours.
- She had been raising the funds in the name of the cause since last week.
- You had been watching Sacred Games for 10 hours.