1) He has never visited Ha Long bay before.
2) She has worked here since last year.
3) Tui khong biet
4) They have played tennis since 2007
5) They haven't visited their home village for five years.
     It is five years since he visited  their home village the last time
6) We have taught at this school for two years
7) I haven't seen Jimmy since Stephen's party
8) Peter hasn't written to his parents for two weeks.