Unit 16. Past perfect continuous(I had been doing)

Yesterday morning I got up and looked out of the window.
The sun was shining but the ground was very wet.
It had been raining.
It was not raining when I looked out of the window. the sun was shining.
But i had been raining before. That's why the ground was wet.
Had been -ing is the past perfect continuous.

You can say the something had been happening for a period of time before something else happened.

• Our game of tennis was iterrupted. We'd been playing for about half an hour when it started to rain very heavily.
• Ken gave up smoking two years ago. He'd been smoking for 30 years.

Had been -ing (past perfect continuous) is the past of have been -ing (present perfect continuous).

present perfect continuous - I hope the bus comes soon.   I've been waiting for 20 minutes. - He's out of breath. He has been running.

past perfect continuous - At last the bus come.   I'd been waiting for 20 minutes. - He was out of breath. He had been running.