Why in this case is the imperfect used although there appears to be a clear time marker, “la semana pasada leía...”? In other examples in this series of lessons phrases like “la semana pasada and el sábado pasado” introduce the preterite. Thanks

Why in this case is the imperfect used although there appears to be a clear time marker, “la semana pasada leía…”? In other examples in this series of lessons phrases like “la semana pasada and el sábado pasado” introduce the preterite.
Thanks

My understanding is that the imperfect is used when the English version would be something like " Last week I WAS READING the newspaper while…". In this case, it seems like that is what the sentence is saying (hard to say for sure without knowing what comes after the “meintras.”

If it had used the preterite (la semana pasada leí el periódico mientras…) the translation would be more like “Last week I READ the newspaper while…”

It is a subtle difference, but definitely different.

Preterite is for simple, completed actions, and imperfect is for on going actions, or processes. Maybe I’m confusing this with other languages, but it seems that the word “while” implies a process is happening over time and therefore talks about the process of reading instead of just completing the action. Another example would be “last week I read the newspaper” which would be preterite. “Last week I was reading the newspaper while riding the train to work” shows that reading and riding were done over a period of time (both actions would be imperfect), and you’re talking about the process of reading instead of just completing the action. If you were to say “Last week I was reading on the train.” it would sound kind of strange to me because you would expect the sentence to go on to say something else. “Last week I dropped a glass” would be preterite, and “last week I dropped a glass while I was cooking in the kitchen” would be preterite for dropping the glass (completed result/action) and imperfect for cooking (process). To make a kind of ridiculous sentence to show it again “Last week while I was cooking (process → imperfect) in the kitchen, I cut (result → preterite) myself with a knife as it was falling (process → imperfect) to the floor.”

One more thing, as Estruch mentioned, is that imperfect can be thought of as saying “I was reading last week” (imperfect) vs “I read last week” (preterite), which are both past tense. Again, the important distinction here is that “I was reading” shows a process or better yet, highlights the process because the process is what’s important for some reason, and “I read” highlights the result (we don’t care about the process in this case and only care about the result).

Thank you for your reply which I completely understand. I think I was focussing too much on the time marker as the “trigger” for the Preterite when the context is probably more important.

Thanks for your reply and a comprehensive explanation of Imperfecto vs. Indefinido. I’m starting to understand that the time markers that “trigger” the indefinido are only guidelines, the context is the real driver. Also on re-reading it, it is talking about parallel activities which I’ve now discovered use the imperfecto for (in this case) both actions.
Thanks again.