Verb conjugation of "specify" in English

Yes, I speak a little bit of English. I'm just beginning to take English courses in private evening classes. Is your Spanish good? I will speak to you in Spanish and you teach me in English.
You have to be careful when you go on summer vacation. There are many dangers but the most dangerous one is the sun itself, because if you're not careful it may harm you. People underestimate the rays.
I once had a lesson with a private teacher, but unfortunately she could not come regularly. She was always sick, then I have visited a school in Andalusia, which was worthless, since we talked only German.