Can someone please explain when we must use the continuous past tense and when the simple past tense and when both are possible?

I have this sentence

(http://www.absolutereturn-alpha.com/Article/1893130/The-bottom-line-is-we-were-paying-20-an-hour-... )

I know that he's referring to some past time when they moved their bussines to China so the use of the progressive seems perfectly ok.

Now I wonder whether these are possible

Back then we were doing fine.

In the past we were doing fine.

In the past/Back then we were paying less for utilities than these days.
IvanhrCan someone please explain when we must use the continuous past tense and when the simple past tense and when both are possible?
Oof! Tall order! That would require a lot of research and probably at least a chapter of a book.

Supposing that those are the only two choices, you have to use the simple form to speak about a finished past action or event - anything that is being framed as a featureless fact or as a block of time uniformly filled with the action or event. Most stative verbs need the simple form as well.

For a period of time during which an activity takes place you'll need the continuous form, though the simple form can often substitute. (This is the hard part.)

IvanhrI wonder whether these are possible
Back then we were doing fine.
In the past we were doing fine.
In the past/Back then we were paying less for utilities than these days.
Wonder no more. They are all fine.

CJ
Thanks, CJ

I asked because I was told that you can't really use the following sentence

In the past we were paying less for mobile phones than these days.

Supposedly it must be

In the past we paid less for mobile phones than these days.
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To be fair, Ivan, let's give CJ a link to the thread in question, shall we?

http://www.englishforums.com/English/ThePast/pqwrn/post.htm
Yes. I was kind of hoping you'd join the discussion. I'm sure you realize that I asked this question again only to satisfy my own curiosity and certainly not to question your grammar expertise.

For me, English tenses are the most difficult point of English grammar and I know that I'm bound to make a mistake now and then and I can live with that. But when I do make a mistake I guess I need a more detailed explanation than just the progressive needs some background situation to justify its use.
OK. I took a look at that link and here's my take on your situation.

IvanhrI was told that you can't really use the following sentence
In the past we were paying less for mobile phones than these days.
Supposedly it must be
In the past we paid less for mobile phones than these days.
Well, actually I don't think this is quite what you were told. What is somewhat objectionable (in my opinion) is In the past we were paying less for mobile phones than we do these days, which is what was in the other post. In other words, it's the change in aspect that bothers me. For me, it's got to be either of these:

In the past we were paying less for mobile phones than we are (paying) these days.

In the past we paid less for mobile phones than we do [or we pay] these days.

I don't find anything inherently objectionable about the tenses in either of those. I would take either one as imperfective in aspect, i.e., some sort of activity or habit that lasted for an unspecified period of time. The idiom used to would do as well in the first clause (... we used to pay less ... than we do ...).

Your versions in the quote box above don't use any form of any verb after than, so there's nothing to object to in either quoted sentence, as far as I can tell.

CJ

PS. I realize that it was they and not we on the other post, but I continued with the we that you used in your example just to keep this thread consistent.
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Thank you so much for your reply.

I did say in my post that the sentences using the progressive were fine as long as you replaced "do" with "are". And I thought that the meaning of "used to pay" was better conveyed with the progressive but I was probably wrong about that.