Dear (имя,которое указано в письме),
I was happy to get your letter. Sorry, I have not written for so long as I was busy at school studying hard for my exams. How are you?
In your letter you ask me about people's environmental contribution in Russia. Young people here work on some environmental projects,including clearing lakes and rivers, planting trees and studying effects of pollution. There is one Green Movement in my town and we get all kinds of support from local community.
By the way, what are you going to do on this holiday? What places do you want to visit? Will you spend holidays with your parents or friends?
Sorry, I have to go now to help my mother about the house. Keep in touch.