Ответ:

Dear Bill,

Thanks for you last letter.

I am staying at London now. I arrived here last Sunday. I am living at home of my pen-friend Mark. It is my first trip without parent.

London is so beautiful city. I have seen many places of interest. Now I am staying neae Big Ben.

The weather is fine. So, I am goining to go for a walk this evening. Mark said, that he know many unknown, but very beautiful places in London. It is my last day in London, so I hope I'll have a good time.

Tomorrow I am going to leave London and return to my home.

Have you ever been to London? What where you doing there? What are you going to do tomorrow?

I am looking forward to yoir answer.