Complete the sentences.Use the present perferct form of the verbs in brackets 1)John(not play) the violin since he was at school
2)mary(study) hard this year,so she'II pass her exams.
3)Tom's my best friend.I___(know) him for three years.
4)My parents(join) Facebook.
5)My sister(buy) a new smartphone
1. haven't played
2. has studied
3. have known
4. has joined
5. has bought