Вот решения для преобразования предложений в косвенную речь:
1. "I can't explain this rule to you," said my classmate to me.
* My classmate said that he couldn't explain that rule to me.
2. "You have done your work well," said the teacher to me.
* The teacher said to me that I had done my work well.
3. He said: "I have just received a letter from my uncle."
* He said that he had just received a letter from his uncle.
4. I said: "I can give you my address."
* I said that I could give them my address.
5. My friend lives in Moscow, said Alec.
* Alec said that his friend lived in Moscow.