1 "I was on the beach yesterday," she said.
-> She said that she had been on the beach the day before.
2 I would like you to send me a letter.
-> Do you mind sending me a letter?
3 It is necessary for him to wear goggles when swimming.
-> He must wear goggles when swimming.
4 He closed the door then he left his office.
-> Before he left his office, he had closed the door.
5 After they had evacuated the victims to safe shelter, they went home.
-> Before they went home, they had evacuated the victims to safe shelter.
6 When did you learn English?
-> How long have you been learning English?