Did you already know why?

In the first sentence Roberto is the subject of the question. “Did Roberto read...?” In the second sentence Roberto is the object of the sentence “I’m going to see Roberto.” The “a” before Roberto is what is called “personal a”. It comes before the direct object if that object is a person. I hope this helps.

In the second one you have 2 subjects and for that reason you need the letter "a" how a connector .... And remember in Spanish the structure different sujeto+predicado -¿Roberto leyó un libro en el avión ?

Hello I'm her if you want to practice with me just send me message Or your ID skayb Or whatssap you find my number whatssap and my ID skayb for my page italki okay By the way ilke your color

Del es la unión de la preposición de y el artículo el. Es recomendable utilizar del en lugar de el, porque a final de cuentas, parece que sólo pronunciamos una sola e. Ej: Lo mejor del curso es que conocí a mi mejor amigo. De él si es diferente porque se refiere a la posesión de alguna cosa para el sexo masculino.