Respuesta :
Yo no entendí nada de la lección ayer.
The simple past perfect is used, because it has no relation to the present. The action has nothing to do with the present, but is in the past.
Yo no entendí nada de la lección ayer.
The simple past perfect is used, because it has no relation to the present. The action has nothing to do with the present, but is in the past.