Answers and Explanations:
First, define each verb: "conocer" means to know people, "saber" means to know information, and "poder" means to be able to.
1. The sentence reads: I don't ________ Susana. Who is she?
Obviously, we'll want to use "conocer" here. Since Sara is talking, we need to conjugate conocer into the preterite yo form: conoci (accent over the i).
2. The sentence reads: She is a friend of Yolanda. I met her at Yolanda's party that you not _______ to go, because you had homework.
Clearly, Paco is trying to say that Sara couldn't go to Yolanda's party because of homework, so we want to use "poder" here. Since Paco is talking to Sara, we need to conjugate poder in the preterite tu form: pudiste.
Hope this helps!
