estaban triturando
-they/you were grinding
Imperfecto progresivo para el sujeto ellos/ellas/ustedes del verbo triturar.

triturar

No me dejaron entrar, pero pude ver que estaban triturando.
They wouldn't let me in, and I could see that they were shredding.
Cuando estaba en el apartamento de Forrest, no pude ver... con claridad la caja de archivos que estaban triturando. ¿Verdad?
When I was in Forrest's apartment, I couldn't see that box of files he was shredding clearly.
Palabra del día
temprano