Answer:
past perfect progressive
Step-by-step explanation:
The past perfect progressive tense is formed by using the past perfect (had + past participle) in conjunction with the progressive form (been + present participle) of the verb. In this sentence, "had been coaching" indicates an action that occurred before another past action and emphasizes the ongoing nature of the coaching. It implies that Gramps had been coaching at the local college for a period of time before he quit and went to work at the bank. I hope this helps!