must have been
Tu muerte no habrá sido en vano.
Your death will not have been in vain.
Oh Señor, me pregunto quién habrá sido el primer tonto que inventó los besos.
Oh Lord, I wonder who the first fool to invent kissing was.
It must have been the same as before.
It must have been someone else.
No sé cuál habrá sido su experiencia con las turistas americanas.
I don't know what her experience with American tourists was like.
— Locuras de verano (1955)