Spanish language Q&A Forum

As stated by one example, "Yo conocí a Susana hace 6 meses."

However, as stated by another, "Hablé con Clara hace 2 horas." 

Why didn't the second example utilize "a"

Is it because "con" had already been used?

Las chicas ________ el desfile de moda. The girls saw the fashion show. (HINT: Conjugate “ver” in El Pretérito Perfecto) without the hint, would vieron be more appropriate? i'm having a hard time differentiating, and would not think preterito perfecto was correct here. additionally, la costurera ha deshecho todos los puntos de la falda - why wouldn't this also just be deshizo? (preterite)? there isn't really anything connecting it to the present ?

Hola Silvia y/o Inma, 

Please could you tell me why the preposition a is used with sobrevivir and yet not used with superar (which was given as an alternative in the hint)? I hope it's not something obvious that my old brain isn't getting, ja ja ja! 

Gracias :)