Tenses Questions
The past perfect continuous tense is used to describe an ongoing action that started in the past and continued up until another point in the past. It is formed by using "had been" + present participle (-ing form of the verb). For example, "She had been studying for hours before she finally took a break."
On the other hand, the present perfect continuous tense is used to describe an ongoing action that started in the past and is still continuing in the present. It is formed by using "have/has been" + present participle (-ing form of the verb). For example, "I have been working on this project all day."
In summary, the main difference between the two tenses is that the past perfect continuous focuses on an action that occurred in the past and continued until another point in the past, while the present perfect continuous focuses on an action that started in the past and is still ongoing in the present.