Montrel, I'll answer in English. Yes, you can use both tenses in one sentence. Your paragraph is interesting because you're explaining your fear of the mountain. When you use "explique," English and Spanish grammar shifts to the next tense: past. We understand the mountain is dangerous NOW, but we explain it with a past verb. This is called "reported speech" ("Where is he going?" Answer: "He said he was going to Florida.") This grammar is interesting, too, because of the meaning of your sentence. Fear can be temporary or it can stay with us. You might be afraid only when you are near the mountain or you might always be in a state of fear. Therefore, the tense can vary. When someone says "I was so afraid" we understand that the person isn't afraid now. In the actual moment, the person said "I am afraid! but later when someone says "What happened?" then the answer is "He was so afraid" (to describe the past fear that does not exist now) or the answer can be "He is so afraid" (to indicate that the fear is part of his personality and it does not go away). In sentences that do not have reported speech, a sentence can have both tenses. Usually a conjunction joins two sentences or a comma separates a clause. All of this depends on the meaning that the speaker wants to give about the tense. Example: If you are free tomorrow, I will pick you up at 10:00. Example: Even though I have been studying Spanish for five years, I still do not know it. I hope that explanation is helpful! MARC