hubieran jurado
-they/you had sworn
Antecopréterito de subjuntivo para el sujetoellos/ellas/ustedesdel verbojurar.

jurar

Si me hubieran jurado que iba a poder saltar sobre el mar como en una cama elástica, dando saltos enormes, volando tan arriba que casi toco los pies de las avionetas Sinceramente, no les hubiese creído.
Had they sworn to me that I would be able to tumble over the sea as if on a trampoline, reaching so high I could almost touch the bottom of small airplanes, I would have never bought into that.
Palabra del día
la canela