"Can you open the door, please?"
Translation:¿Abres la puerta, por favor?
you spend years learning to use poder and now it disappears, very confusing!!
To make a request in English, we usually add words like "will" or "can" to be polite. DuoLingo is trying to teach that in Spanish you can more direct and leave out those words when making a request. Duo shouldn't mark it as wrong if you include it though.
This seems to be a thing, where the verb "poder" is not used. It would be nice if someone could explain why, especially as other sites accept ¿Puedes abrir le puerta, por favor?