1)"Can you help me?" She said to me.
--->She asked if I could help her
2)"Can you explain the answer to me again, Lan?"Mai said
--->Mai asked If i could explain the answer to her again
3)"Please tell your son to write the lessons carefully, Mrs. Brown"Mr. Gates said
--->Mr.Gates asked Mrs. Brown to tell his son to write the lessons carefully
4) why don't you finish the work soon
--->You ought to finish the work soon
5)She said to him ,Don't leave your coat on the chair".
--->She told him not to leave his coat on the chair