What Had Been Happening Before Something Occurred
Past Perfect Continuous
The past perfect continuous expresses the duration of an activity up to another point in time in the past. The use of the past perfect continuous stresses that a certain activity had been going on before something important happened.
Example:
John had been working on totalling the amount of his liquid assets when the phone rang.
How long had you been studying information technology before you decided to switch to finance?
She had been doing well financially until she wrote a bank draft for more than was in her account.
Positive Form:
Subject + had + been + 'ing' form of verb + (object(s)) + time expression
The economy had been struggling through a bear market for so long that people didn't know how to react.
Negative Form:
Subject + had + not + been + 'ing' form of verb + (object(s)) + time expression
They hadn't been using that credit card account long when they used up their card's limit.
Question Form:
(Question Word) + had + subject + been + 'ing' form of verb?
How long is it going to take them to decide on the take over bid so we can start real work
Past Perfect Contrasted with Past Perfect Continuous
The past perfect expresses something that finishes before another activity in the past. The past perfect continuous, on the other hand, expresses the duration of an activity at the moment something important happened in the past.
Past Perfect Examples:
How fast had the company been in finalizing any take-over bid earlier?
I had already seen the net assets before he announced them to the group.
Past Perfect Continuous Examples:
They had been explaining the fixed exchange rate when the officer entered the hall.
How long had you been studying information technology before you decided to switch to finance?