"I need the letters for Monday."
Translation:Yo necesito las cartas para el lunes.
Because you're talking about a specific day of the week here - Monday, rather than Mondays in general which wouldn't need a preposition.
In Spanish, on the other hand, when you want to talk about something happening on a specific day of the week, you must use a definite pronoun before the day of the week. The days of the week are always masculine, so you’ll use either el or los.
When talking about one specific day of the week, use el.
Iré a Bogotá el lunes que viene. (I will go to Bogota next Monday.)
When talking about something habitual, or something that happens every week, use los.
Voy al gimnasio todos los martes. (I go to the gym every Tuesday.)
In that context 'lunes' is simply describing what 'manana' is. We are talking about 'tomorrow' as opposed to 'Monday' specifically. So no article needed.
In Duo's sentence 'lunes' is the object of a preposition. So the article is needed.
Please someone correct me if I got any grammar wrong here.
"Today" is a particular day so why not "el lunes", it's confusing about half the time i get marked wrong - it seems like its guessing more than any way of knowing - i have met native speakers from different parts of the world who also don't use "el" in this phrase "necesito las cartas por lunes"
I learnt from a Paul Noble Spanish CD that you use 'por' when describing how 'long' something is for, like a duration. "...por dos noches" ... For two nights. You use para for possesion, "para mi" ... for me. Im sorry I cant explain it in more detail im a learner myself
Two good links: Para = for (preposition) Por = for, in, by (preposition)
Yes, the monday, opposed to the mondays. Lunes doesn't indicate general or a specific day. So you need el or las to clear the ambiguity.
That applies to all days of the week even though other days could appear plural without because those words can be modified with an 's' To keep it consistent they all need to be stated in the same way. It can't be done differently because of the days of the week only saturday and sunday don't end with an s. lunes martes miércoles jueves and viernes all do. You see?
Most the days don't have any other way for you to talk of them in general terms or solo terms unless you add the definite articles because of the structure of the words.
Hope that helps.
why when I hover over "the" the pop-up shows "el" instead of "las." I typed in "Yo necesito el cartas para lunes." It marked me wrong even though I used what was shown in the pop-up. I still would have had it wrong for not putting "el" in front of lunes. However, why can't the pop-up show the correct word to properly use?
El is the, but so is los y la y las. You put the appropriate version of "the" in spanish according to the word it is attached to. It has to match gender and quantity. You should know this by this point in duolingo. Though they don't exactly explain things in the lessons. Take some time to read comments on the more difficult ones. Often you find great answers here.
Because we are only talking about one Monday. It is not plural.
Edit I occurs to me that the ending 's' is confusing you. The word 'lunes' means Monday. The 's' is part of the word.
el lunes = the Monday
los lunes = the Mondays
Notice in both the singular and plural the word retains the 's'.
This is a deadline. So 'para' is the right choice. The following might help you here:
Think of 'para' as a straight arrow imparting a direction of sorts with a final destination. Use 'para' for Deadlines, Destinations, Goals, and Recipients. In fact if you are in doubt which to use in a conversation... use 'para'. Most of the time it will be right.
Think of 'por' as a squiggly line or an X. It imparts and 'exchange' or 'motivation' of sorts without the clear ending or destination that 'para' had. Use 'por' for Communication, Duration, Exchanges, Motivation, and Travel.