"I am walking to the door."
Translation:Estoy caminando a la puerta.
Differently than english, in spanish we have two verbs to express "to be", for example "yo soy" is used to express how is your personality, or a "permanent" state of you. Calm, careful, happy, patient would be adjectives to use with "soy". In other hand, "estoy" means the moment, how you are right now: I'm using this clothes, I'm sad because someone died (usually I'm a happy person), I'm running (usually you walk)... I hope you get it ;)
I use the following memory aid, SER: Description, Occupation, Characteristic, Time, Origin, Relationships (DOCTOR), Estar: Position, Location, Action, Condition, Emotion(PLACE). In this case it is an action. That requires "estar"(estoy here).
Ando a la puerta would equate to "I walk to the door" which is not the present progressive and is not the translation required by the given sentence.
I'm sorry to see that your question has been ignored for the last eight months. You probably know the answer by now, but for others still wondering:
You can, but this is a lesson on gerunds; so you might say Estoy andando a la puerta. I don't know whether DL accepts this.
However, I understand that caminar means to walk somewhere for a specific purpose, whereas andar means to walk around (as well as several other meanings). It's a good idea to check it out yourself in the dictionary and other reference books.
Why isn't "Estoy caminado hasta la puerta" correct? "I'm walking to the door" could not only mean that I'm walking towards it, but also that I'm walking to go to the door and that I'm not going anywhere beyond that. Is "hasta" so incorrect for this case?
Why is it wrong to put "Yo soy" instead of "Estoy"? I unsure of the difference, thanks in advance for any help!
The "yo" is optional, but not normally used since the verb form (soy or estoy) already indicates the "yo". Regarding your question, soy is very different from estoy (ser vs. estar) and estar, and not ser, is used with the gerundio - the -ando / -iendo form of the verb.
I don't think that "pasar" can stand for "walk". Maybe you thought of "pasear" - but this has the meaning of walking for pleasure, taking a walk, it would seem strange to take a walk to the door