"Finalmente la puerta se ha abierto."
Translation:Finally the door has opened.
It is not reflexive it is passsive voice. A reflexive action is one the is done to oneself by oneself. The action starts and ends with the same person. A sentence in passive voice is an action that is done by some unknown force or we are not told how the action took place. Se is always placed in front of the verb never attached to the infinitive, and always used in the third person singular, so no te's or me's. whereas reflexive uses me, te, nos, os and se.
Yes because they come from the same root. It's a simpler, cleaner, perhaps most literal translation with the least chance of a personal bias changing the meaning. And because it's easier to work with DL by choosing the most obvious translation rather than struggling to teach the Owl alternate ones. But that's just me. To each his own. Cada loco con su tema. ;)
I was playing safe here so that I would not be marked wrong. But I think 'se ha abierto' has a passive meaning in this context and should be translated by 'has been opened'. Passives are rarely used in spoken Spanish and French. Usually the reflexive 'se' structure is used.
If i actually knew how grammar works then i would be able to understand when something is a verb or adjective or any of the other language nonsense that makes it so hard to make a sentence, but i don't so most of the time when someone starts to explain something and say " its a noun" basically it is just gobbledejook to me hahahaha
It is very difficult to explain how languages work without using the vocabulary of grammar. I do appreciate that that makes it difficult if you haven't done much grammar before. And Duolingo does assume we understand the basics of grammar.
I suggest you find some good grammar websites and start from the beginning --- "A verb is blah, blah, blah", "A noun is etc etc", even if you already know some of it. Even if you do already have some basic grammar it will be time well invested. And it doesn't take long to skim through the basics when you already have some knowledge (which you clearly do - even though the way we talk about it may not be familiar).
I started learning Spanish and revising my rusty old French four years ago. Even though I had studied English grammar (and Latin and French - albeit numerous years ago!), my confidence that I knew it all already was sadly misplaced. It wasn't long before I was checking my understanding and finding several large holes! And four years on, I still check the grammar websites regularly. It is a lot easier now I know my way around them.
I dare say I could recommend some good grammar websites, but I suggest you start like I did. Google "English grammar" and see what it throws up. You will soon learn how to spot the rubbish ones and build up a favourites list for the ones worth going back to. (PS: other search engines are available!)