12. I started cooking for the party 2 hours ago.
 I have___________________________________________________________________
13. She started to work as a doctor 6 years ago.
 She has _________________________________________________________________
14. My father is reading a newspaper. He started an hour ago.
 My father _______________________________________________________________
15. It is years since my sister used English.
 My sister has ____________________________________________________________
16. Scientists began fighting against SARS-CoV-2 in 2019.
 Scientists have ___________________________________________________________
17. The Browns began living in London 20 years ago.
 The Browns have _________________________________________________________
18. John started to work for this company in 2019
.  John has ________________________________________________________________
19. He started planting flowers some years ago.
 He has __________________________________________________________________
20. Many students in Phu Tho started to study online some months ago. 
Many students in Phu Tho have _________________