Past Perfect Continuous Tense

What is Past Perfect Continuous Tense:

Past perfect continuous tense is used to talk about an ongoing past action or situation that continued for a long time in the past.

Example Sentences:

It had been raining since morning.
He had been sleeping for 10 hours.
She has been playing since evening.
They have been watching the movie for 2 hours.
The girls had been quarreling over the toy for half an hour
when we arrived home.
The road was wet because it had been raining. (for a long time)
If it hadn't been raining, we would have gone to the park.

Structure of Past Perfect Continuous Tense:

Positive:

Subject + had been + 3rd form of verb + since/for....   .

He + had been + studying + since morning.

Negative:

Subject + had not been + 3rd form of verb + since/for....   .

She + had not been + playing + for 3 hours.

Interrogative:

Had + subject + been + 3rd form of verb + since/for... ?

Had + she + been + running + for 1 hour?