Вот пример ответного письма для вашего друга Дэвида:
From: Russian_friend@mail.ru
To: David@mail.uk
Subject: Re: Friendship
Dear David,
Thank you for your letter! I’m glad to hear from you. At school, I have many friends. After classes, we often go to the park or the cinema together. In the evenings, we usually text each other and sometimes have phone calls to talk about our day. I hope you make more friends soon. Write back when you can!
Best wishes,
[Ваше имя]
Обратите внимание, что в письме соблюдены правила написания: вежливое приветствие, благодарность за письмо, ответы на вопросы и прощание.