This document discusses the past perfect continuous tense in three sentences: The past perfect continuous tense describes an activity that was ongoing and completed at some point in the past. It uses the verb phrases "had been" plus the "-ing" form of the main verb (e.g. "had been sleeping"). The past perfect continuous tense is used to talk about an activity that was happening continuously up until another time in the past. It can be used with all subjects and includes adverbs of time like "when", "since", "for", "before", and "after".