Translation of desgarrón

The script I am writing will shuffle the 1.5 million words and it will detect if too many words are from the same user. And if an entry is too long, I will skip it and rely on the sentences that we can hopefully make up together.
On the frozen lake, you can skate, but I would never dare it because it is far too dangerous. Who knows how thick the ice really is and how accurate the measurements are. It can break.
What is the past tense of 'to swim'? So either you say, I was swimming or yesterday I was swimming. Or: I was running yesterday vs. yesterday, I ran. You know the answer? I have no clue.