a matter of
Hay gente que piensa que los hijos son cosa de un día.
Some people think that children are a one-day thing.
— Todo sobre mi madre (1999)
Debe haber sido cosa de su hermana.
It must have been his sister’s doing.
En las cosa de la vida hay sueños y deseos.
In the things of life, there are dreams and desires.
— Una historia china de fantasmas (1987)
Esto parece cosa de terrorismo.
This looks like an act of terrorism.
— Mujeres al borde de un ataque de nervios (1988)
It will be a matter of a couple of days.