Well, you check memory very briefly, make a quick scan, and it's awfully easy to say to yourself, Ring, Rang, Rung, and very hard to say to yourself, Pare, Park: they come more slowly.
Bien, comprueban su memoria, repasan rápidamente, y es muy fácil decirse "Ring", "Rang", "Rung", y muy difícil decirse "Pare", "Park": vienen más lentamente.