Translation of refinar

At noon the oldest soon came home. He was a doctor and gave me some salt and other Cuban medicine. I was reluctant to swallow that stuff but the pain and the doctor's smile persuaded me in the end.
Let me summarize our meeting from Sunday, please give me feedback if something is unclear. I will send you the study material, including lessons and vocabulary lists to ensure the accuracy of training.
In order to get to this hidden lake one would have to row beneath a cave. On the other side of the cave the five of us were alone. The lake was surrounded by limestone mountains covered with tropical trees.