Form	Structure	Example
Affirmative	subject + had + been + present participle	I had been studying for three hours.
	verb	They had been working on this project.
		She had been practicing the piano.
Negative	subject + had + not + been + present	I had not been exercising regularly.
	participle verb	They had not been attending meetings.
		She had not been feeling well.
Question	Had + subject + been + present participle	Had you been learning a new language?
	verb	Had they been working on this project?
		Had she been taking dance classes?

Past Perfect Continuous is used to describe an action that started in the past and continued up until another point in the past.

It emphasises the duration of the action and often suggests that the action was ongoing and unfinished at the time of the past event.

Usage:

To describe a past action that started before another past action and continued up until that point:

I had been studying for three hours before I took a break.

To describe a past action that continued up until a specific point in time in the past:

They had been working on this project for weeks before they completed it.

To describe a past action that was ongoing and unfinished at the time of a past event:

She had been practicing the piano all morning before she stopped.

To describe the cause of a past situation or event:

I had been feeling sick for a few days before I went to the doctor.

To express irritation or annoyance about a past situation or action:

He had been talking non-stop for hours before I finally interrupted him.

In general, Past Perfect Continuous is used to show the duration of a past activity or situation, often in relation to another past event.

It can also be used to give context or background information about a past event or situation.

Usage Situation	Example Sentences
Action started before another past action and continued up until that point	I had been studying for three hours before I took a break.
Action continued up until a specific point in time in the past	They had been working on this project for weeks before they completed it.
Action was ongoing and unfinished at the time of a past event	She had been practicing the piano all morning before she stopped.
To describe the cause of a past situation or event	I had been feeling sick for a few days before I went to the doctor.
To express irritation or annoyance about a past situation or action	He had been talking non-stop for hours before I finally interrupted him.

Adverbs in Past Perfect Continuous:

Adverbs can be used in Past Perfect Continuous to provide additional information about the duration, frequency, or intensity of the action being described.

Some common adverbs that can be used in Past Perfect Continuous:

For:

This adverb is often used to indicate the duration of the action being described, such as:

I had been studying for three hours before I took a break.

Since:

This adverb is used to indicate when the action started, such as:

They had been working on this project since January.

All day/night/week/month/year:

These adverbs are used to indicate the duration of the action being described, such as:

She had been practicing the piano all day.

Continuously:

This adverb emphasises that the action was ongoing and uninterrupted, such as: