over a period up ??

We use the past continuous tense for an action or situation that was in progress at a particular time in the past.

I met her when we were working for the same company. (past continuous tense)

You can use the past perfect continuous tense to say how long something had been happening before something else happened:

Peter had been smoking for 30 years when he finally gave it up.

Compare the past perfect continuous (I had been doing) with the past continuous (I was doing):

* When I looked out the window,it had been raining. (= It wasn't raining when I looked out; it had stopped.)
* When I looked out the window,it was raining. (= Rain was falling at the time I looked out.)

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