Ответ:

1. I cannot find a letter which you gave me this morning. 2. Yesterday I spoke to man who had just returned from the Arctic expedition. 3. The clock in the hall is slow. 4. I have received a letter of great importance. 5. I have bought an overcoat with a fur collar. 6. She was still thinking of the letter she had received that morning. 7. The magazine which you lent me is very interesting. 8. This is a picture which you will like. 9. Yesterday I met an old friend, whom I recognized at once. 10. This morning the postman brought me a letter without stamp. 11. I know the man who lives in the house where you live. 12. Is that a man whom they are looking for? 13. My son has a very good German teacher, who knows the language perfectly. 14. A person who is sitting next to me is a famous painter.

Объяснение: мой английский нельзя назвать идеальным, но я надеюсь что смогла чем-то помочь.