Respuesta :
Answer: The event took place in the past continuously but concluded prior to another past event.
Explanation:
The past perfect continuous tense uses 'had been' + the verb’s present participle (root + -ing) to reveal that an event that began in the past, lasted until another event, also in the past. It´s a verb tense that shows something that occurred continuously during the past and ended at a specified time in the past.
In this example, we know that, at first, Gramps had been coaching for a continued period in the past, until he quit and went to work at the bank (also in the past).