11. "The sun rises in the east and sets in the west", my teacher said.
=> my teacher said that the sun rised in the east and sets in the west.
12. My friend said," I have already written this letter".
=> My friend said that she had already written that letter.
13. Carol said to me, "I will ask Mr. Wilson about this lesson the next day".
=> Carol said to me that he would ask Mr. Wilson about this lesson the next day.
14. Her friend said to her, "I don't understand these lessons carefully".
=> Her friend said to her that she didn't understand these lessons carefully.
15. Mr. Quang said,"I must leave right now".
=>. Mr. Quang said that he had to leave right then.
16. Charles said to Jane, "I have to leave the office before 3.30 pm"
​=> Charles said to Jane that he had to leave the office before 3.30 pm.
17. Mary and John said, "We don't know those two girls very well"
=> Mary and John said that we didn't know those two girls very wel.
18. Jimmy said to Maryam, "I have given you this bike twice"
=> Jimmy said to Maryam that he had had given you this bike twic.