1. I / know / her / a long time

-> I have known her for a long time.

2. They / buy / new house / April

-> They have bought the new house in April.

3. My family / be / here / Christmas

-> My family has been here since Christmas.

4. We / not see / each other / 10 years

-> We haven't seen each other for 10 years.

5. How long / you ever / visit / Ha Long Bay ?

-> How long have you ever visited in Ha Long Bay?

6. I / write / letter / 2 hours

-> I have written a letter for 2 hours.