Verb conjugation of "sterilisieren" in German

By the way: I have now met a man who claims he is an expert in deep snow skiing... I find that very impressive for someone with only 3 years of snowboarding experience. It is probably just showing off.
My correction were added and highlighted with yellow markers and attached to this email. Tell me now if you have any questions about grammar rules, since I was a teacher 10 years ago.
I need to learn a lot of Spanish because I want to study at the university of Madrid. In Switzerland, I studied law, but after 2 years I have switched to medicine: to help people, rather than you know....