Translation of Messerschmied

It actually happened to my cousin's youngest kid. He was repeatedly warned not to smoke in the courtyard of the school. At the end he found himself expelled from the school. It could have been an interesting experience for him though.
Please explain me the exact differences between British and American .... This year I'm trying to make the TOEFL. We can then discuss how we can prepare for this exam. I failed the first time.
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.