must have done it
Un hombre tan inteligente como Ud. debe haberlo considerado.
A man as intelligent as you must have considered it.
Alguien más debe haberlo abierto.
Someone else must have opened it.
Apuesto a que uno de vosotros debe haberlo cogido.
I bet one of you must have caught it.
— Los cuatrocientos golpes (1959)
Alguien que sabe bien inglés debe haberlo escrito.
Someone who knows English well must have written it.