about what
Tener cuidados sobre qué y cuánto comemos es esencial para una buena salud.
Being careful about what and how much we eat is essential for good health.
Ni siquiera puedo recordar sobre qué estábamos peleando.
I can't even remember what we were fighting about.
Tomás está escribiendo un ensayo no sé sobre qué.
Tomás is writing an essay, I don't know what about.
No recuerdo sobre qué estábamos hablando.
I don't remember what we were talking about.