The past perfect continuous and the past perfect

Study these sentences with the past perfect continuous:
• They had been expecting the news for some time.
• She had been wearing high-heeled shoes, and her feet hurt.
• Mason was arrested, even though he hadn't been doing anything illegal.
We use the past perfect continuous when we talk about a situation or activity that happened over a period up to a particular past time, or until shortly before it.

We use the past perfect continuous when we talk about the continuity or duration of a situation * or activity, and the past perfect to talk about the completion of a situation or activity or its effects.
Sometimes the difference between them is simply one of emphasis (see also Unit 8A):
• I'd been working hard, so I felt that I deserved a holiday, (emphasises the activity)
• I'd worked hard, and the report was now finished, (emphasises the result)
If we talk about how long something went on up to a particular past time, we prefer the past perfect continuous. If we talk about how many times something happened in a period up to a particular past time, we use the past perfect:
• They had been travelling for about 36 hours, (rather than They had travelled...)
• We had been looking at the painting for about ten minutes before we realised who the artist was. (rather than We had looked...)
• I'd heard the symphony many times before, (not I'd been hearing...)
• The teacher had let them get away with their bad behaviour once too often, (not ...had been letting them...)
However, some verbs that describe states (see Unit 2A) are not often used with continuous tenses, and we use the past perfect with these even when we are talking about how long something went on up to a particular past time:
• I had always believed that it would be easy to get a job. (not I had always been believing...)
• We had owned the car for 6 months before we discovered it was stolen, (not We had been owning...)
Compare the use of the past perfect continuous and past continuous:
• When we met Simon and Pat, they had been riding. (= we met after they had finished)
• When we met Simon and Pat, they were riding. (= we met while they were riding)
• When I got home, water had been leaking through the roof. (= it was no longer leaking when I got there)
• When I got home, water was leaking through the roof. (= it was leaking when I got there)