6. I haven't met Hoa since her family moved to England.
→ The last time I met  Hoa was when her family moved to England.
→ I last met Hoa when her family moved to England.
7. It is the first time Phong has come to class on time.
Phong has not come to class on time before 
8. We last went to the cinema 2 weeks ago.
→ We haven't gone  to the cinema for 2 weeks .
9. She hasn't visited me since we were in Ha Noi.
→ She last  visited me  when we were in Ha Noi
→ The last time.she visited me was when we were in Ha Noi