Did it snow this time last year? seems a little too specific. I would take it almost as
Did it snow on this date last year? Hardly anyone would remember such a thing. I think, therefore, that unless I were consulting a meteorologist regarding real weather data, I would use
Was it snowing this time last year? because it suggests an entire, but approximate, time period during which some snowing activity may have happened.
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G was playing football at 6 suggests that G was playing football between, maybe, 5 and 7. The football playing activity was in progress when the clock struck 6.
G played football at 6 suggest that G had, maybe, an appointment to play football at 6. The game started at 6.
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We were living there at the time sounds like a set-up for something more. It's descriptive. It's setting the scene for something that happened, most likely during that year, 1998. That was lucky, because the big cities had food shortages that year.
We lived there at the time sounds like a final statement. There's nothing more to be said. We lived there. Period. We've finished talking about 1998. Let's move on now to what we did the next year. In 1999, we moved to a big city.
In the specific cases you have here, I think the place "we were living" is emphasized more, and the year "we lived there" is emphasized more.
That said, with a stative verb like live, the difference between simple and progressive tenses is minimal.
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Ten minutes later I was still waiting for the tram is the only one of the two that is possible. That's because of still, which seems to beg for the progressive tense. We were still [living, waiting, staying, working, resting] there. still implies a continuity of activity which is contradicted by the use of the simple tense.
Ten minutes later I was waiting for the tram suggests that finally, after ten minutes of various other events or activities, I arrived where I began the waiting process, which lasted for some unspecified amount of time.
Ten minutes later I waited for the tram is a little anomalous because waiting is by nature continuous and couldn't have happened all at once at the point in time indicated by ten minutes later.
I waited for the tram for ten minutes is normal. It conceptualizes the full ten minutes as "closed" and entirely "filled" with the ten-minute waiting event.
I was waiting for the tram for ten minutes is a little anomalous. The period of ten minutes is "closed" or "bounded", so it doesn't mix well with an "open", "unbounded" tense.
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Unfortunately, what you learn about the subtleties of one verb does not necessarily apply to the use of any other verb. Each verb has its own grammar, and sometimes a verb does not act the same as any other verb when it comes to the nuances of the tenses it appears in.
CJ