Answer:
Somos
Explanation:
You would use the we form of ser.
(Ellos) Acabaron de escribir la carta.
You can omit "ellos" if needed
Answer:
estas
estan
estoy
estamos
esta
Explanation:
yo(I)=estoy
tu(you)=estas
el,ella, usted (he, she, or you(formal))=esta
nosotros(we)=estamos
vosotros(y'all (spain only))= estais
ellos, ellas, ustedes (they, they(female only), y'all(formal))=estan
By reading the sentence I would put
A mi maestro le gusta escribir en la pizarra.
But, there are many adjectives in Spanish that would suit this sentence. Tell me if this is what you need, if not let me know....