1.My sister has worked here for ten years.

2.we have started to play the piano for nine months.

3.They have begun to live in Hanoi since 1990

4.Minh has begun collecting stamps since last year

5.He has begun to study English since he was young

6.I have not written to my uncle since July.

Answer :

1.My sister has worked here for ten years.

2.we have started to play the piano for nine months.

3.They have begun to live in Hanoi since 1990

4.Minh has begun collecting stamps since last year

5.He has begun to study English since he was young

6.I have not written to my uncle since July.

( mình ko chắc lắm nhé !)

Good luck !