Tenses Questions
The present perfect continuous tense is used to describe an action that started in the past and is still ongoing in the present. It emphasizes the duration or continuity of the action. For example, "I have been studying for three hours."
On the other hand, the past perfect continuous tense is used to describe an action that started in the past, continued for a period of time, and was completed before another past action or point in time. It emphasizes the duration or continuity of the action in relation to another past event. For example, "She had been working all day before she finally took a break."
In summary, the present perfect continuous tense focuses on an ongoing action from the past until the present, while the past perfect continuous tense emphasizes the duration of an action that occurred before another past event.