Complete Anna's letter to a magazine. Use the present simple of the verbs the box.not know, not say, not talk, not understand,

I don’t understand the lessons. I think my brother knows, but he doesn’t say anything. We don’t talk about our problems. I often talk to my friends on the Internet about it. They help me a lot. They don’t know my real name, so I can tell them everything. I don’t want to tell my parents about it, but they know I\'m not happy. What\'s your advice? Anna