Should I use "dans" or "en" here?
"Je dois terminer mon cours ____ un mois."
"Je dois terminer mon cours en un mois" -> It means you ONLY have one month to do your course.
"Je dois terminer mon cours dans un mois" -> Next month, you'll have to finish your course.
In fact those words exist in Spanish : "dans" is almost like "dentro" and "en" is almost like... "en".
But in French, the difference between the period and the event is also present in some other words for instance :
un jour (event/a point in a time line) - une journée (period)
un soir (event/a point in a time line) - une soirée (period)
It's true that's not a very used word. I often hear "en" instead of "dentro". Maybe because "dentro" is only used for ubication.
Thanks for bringing this up! Could you please explain the difference between jour/journée, soir/soirée, etc. I've always been puzzled on when to use which form of the time. Merci!
J'ai dormi toute la soirée. This lasts during all the evening so you use soirée.
Je suis arrivé à la station le soir. You arrive at a precise hour or moment, then you use soir.
Also, "en" expresses something that takes a continuous amout of time: "je dois écrire mon livre en deux mois" - while "dans" tends to be an event in the future: "je dois me marier dans un an"
I'd use dans here, but cannot explain why. And I am not a native speaker, of course.