"Your dog is eating cheese!"
Translation:Wasz pies je ser!
You do if it's a possessive :) e.g. "vuestro coche"/"vuestros coches". Or at least we were taught that in school! I know that in Spain they tend to omit "vosotros" and "tú", but I'm pretty sure "usted" is predominantly used in Latin America. We were taught Peninsular Spanish so "usted" never appeared in any of my lessons until I went to university in Bristol where one of my lecturers was Mexican :P