TENSES

PAST PERFECT CONTINUOUS

Past perfect continuous, form
The past perfect continuous is composed of two elements - the past perfect of the verb to be (=had been) + the present participle (base+ing).

Examples:

Subject	had been	verb-ing
I	had been	walking

Affirmative
She	had been	trying
Negative
We	hadn't been	sleeping
Interrogative
Had you	been	eating
Interrogative negative
Hadn't they	been	living

Example: to buy, past perfect continuous

Affirmative	Negative	Interrogative
I had been buying	I hadn't been buying	Had I been buying?
You had been buying	You hadn't been buying	Had you been buying
He,she,it had been buying	He hadn't been buying	Had she been buying?
We had been buying	We hadn't been buying	Had we been buying?
You had been buying	You hadn't been buying	Had you been buying
They had been buying	They hadn't been buying	Had they been buying

Past perfect continuous, function
The past perfect continuous corresponds to the present perfect continuous, but with reference to a time earlier than 'before now'. Again, we are more interested in the process.

Examples:

a. Had you been waiting long before the taxi arrived?
b. We had been trying to open the door for five minutes when Jane found her key.
c. It had been raining hard for several hours and the streets were very wet.
d. Her friends had been thinking of calling the police when she walked in.

This form is also used in reported speech. It is the equivalent of the past continuous and the present perfect continuous in direct speech:

Jane said "I have been gardening all afternoon." Jane said she had been gardening all afternoon.

When the police questioned him, John said "I was working late in the office that night." When the police questioned him, John told them he had been working late in the office that night.