Answer:
Ella siempre se caía.
Step-by-step explanation:
The text is about a girl called Patty, it tells us a brief physical description of her and the activities she used to do as a child. We can find the answer to the question ¿Qué pasaba cuando Patty corría? in the third sentence of the text: “Cuando corría, siempre se caía y se lastimaba sus rodillas,” which means “When she ran, she would always fall and hurt her knees.” So, what did use to happen when Patty ran? The answer is that “Ella siempre se caía”