Answer:
Past perfect progressive
Explanation:
The past perfect continuous tense (also known as the past perfect progressive tense) shows that an action that started in the past continued up until another time in the past. The past perfect progressive tense is constructed using: had been + the verb's present participle (root + -ing).
So the general form of past perfect progressive/continuous is:
Had +been+ verb +ing.
Hope this helps you, have a great day