Más oraciones... (Ejercicio 6-4)

[laepelba]

Two more sentences that I translated and have questions about.

#2
Given English sentence: While I was singing, Juan came into the room.
My translation: Mientras yo cantaba, Juan entró la sala.
The "answer" from the back of the book: Mientras y cantaba, Juan entró a la habitación.
Question: Why is the "a" necessary? I know that you need "a" if the object is a living being, but why in this case?

#3
Given English Sentence: My boss had been on vacation for three weeks.
My translation: Hacía tres semanas que mi jefe era en las vacaciones.
The "answer" from the back of the book: Hacía tres semanas que mi jefe estaba de vacaciones.
Question: Is "de" always used with "vacaciones"?

[Rusty]

Two more sentences that I translated and have questions about.

#2
Given English sentence: While I was singing, Juan came into the room.
My translation: Mientras yo cantaba, Juan entró la sala.
The "answer" from the back of the book: Mientras yo cantaba, Juan entró a la habitación.
Question: Why is the "a" necessary? I know that you need "a" if the object is a living being, but why in this case? Some verbs are always followed by a preposition (and some never have one where English does). This link (http://www.elearnspanishlanguage.com/grammar/verbs/verbswithprep.html) ought to help you. Click on the 'Verbs with a' link under the 'Verbs followed by an object' heading.

#3
Given English Sentence: My boss had been on vacation for three weeks.
My translation: Hacía tres semanas que mi jefe era en las vacaciones.
The "answer" from the back of the book: Hacía tres semanas que mi jefe estaba de vacaciones.
Question: Is "de" always used with "vacaciones"? Yes.:):)

[laepelba]

Thanks!!