it is not known
No se sabe si alguien le ayudó.
It is not known if anyone helped him.
No se sabe qué sucederá en el futuro.
It is unknown what will happen in the future.
Dijo que no se sabe qué va a pasar.
He said that it is not known what will happen.
Los campos chinos, no se sabe, pero digamos veinte millones.
The Chinese fields, we don't know, but let's say twenty million.
— Les invasions barbares (2003)
No se sabe nada, es muy secreto.
No one knows anything; it’s very secret.
— La Nuit américaine (1973)
Realmente no se sabe nada acerca de la muerte.
We really don't know anything about death.
No se sabe si se suicidó o si fue asesinado.
It is not known whether he committed suicide or was murdered.