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Dear "имя"
Thank you for your letter. sorry, that I haven't been in touch for so long.
My family recently moved in London. It's truly fantastic town. I feel myself as I was born here. I think, it's the best plase to visit and to live, of course.
Also, I have made some new friends here. All of them are our neighbours. They're very likeable and supportive people. I enjoy spending time with them. On weekends we always go shopping together.
Tomorrow will be my first day in new school. I hope, my classmates will be pleasant peple, who will treat me as an old friend.
Sorry, I have to stop writing, because my mobile phone is ringing.
All the best,
Твое имя (без точки)