Change the following sentences from direct into indirect speech

1. my friend said to me: "explain to me how to solve this problem."

2. he said to me: "don't leave the room until i come back."

3. "i can't explain this rule to you” said my classmate to me

4. he said "we have bought these books today.”

5. he said to them: "how can i get to the railway station? "

6. i said to my friends: "when are you leaving st.petersburg? "

7. she said to me: "have you sent then a telagram ? "

8. mother asked me: "did you play with your friends yesterday? " said my elassnate to me