Verb conjugation of "niederreißen" in German

After next week, I will tutor the Mr. Zillmay from the language lab in Los Angeles, he is currently in the states. The lesson will take place in LA, but it may be held no earlier than mid-February.
In school, I had also learned Latin but it's been more than forty years ago. I grew up in Bern and I had lived there all my life, I had no opportunities to travel. It was not that easy during the war.
Thank you for your kind message. I have not done anything for my Spanish because I have too much work at my job. I might write you a letter, but I'm so busy at work that I can't afford other hobbies.