Past perfect continuous tense
Usage
Duration of an action that started in the past and continued until another past moment: The past perfect continuous tense is used to describe an action that started in the past and continued up until a specific past moment.
I had been studying for this exam for three hours before I took a break.
Emphasis on the duration of the action: The past perfect continuous tense emphasizes the duration of an action rather than the completion of it.
I had been practicing my guitar every day for the past year before I decided to take a break.
Connection between two past actions or events: The past perfect continuous tense is often used to describe an action or situation that was ongoing before another past action or event happened.
I had been working at the company for five years before I decided to quit.
Form
The past perfect continuous tense is formed using the past perfect of the auxiliary verb have followed by been and the present participle (-ing form) of the main verb.
I had been studying for my exam.
Signal words
The past perfect continuous tense is typically used with active and dynamic verbs that describe ongoing actions, such as study, work, run, or swim.
Negative and question forms
To form negative sentences in the past perfect continuous tense, the word not is placed between had and been
I had not been studying for my exam.
To form questions in the past perfect continuous tense, the auxiliary verb had is moved before the subject
Had you been studying for your exam?