he couldn't
Tomando todo en consideración, él no pudo ser el criminal.
Taking everything into consideration, he couldn't have been the criminal.
Debido a que surgió un asunto urgente, él no pudo ir al concierto.
Because an urgent matter came up, he couldn't go to the concert.
He couldn't stand the heat.
He couldn't believe his luck.
He couldn't have done that.
Él no pudo abandonar a su amigo en dificultades.
He could not abandon his friend in trouble.
Él no pudo conseguir el trabajo.
He couldn't get the job.
Él no pudo cumplir la promesa que hizo a su padre.
He couldn't keep the promise he made to his father.
He couldn't have said that.
Él no pudo hacer nada salvo mirar.
He could do nothing but watch.