4. Scientists _______have found_______ (find) more than 30 unknown insects.
5. She ________hasn't seen__________ (not see) Nathan since he left the town.
6. Someone ________has broken________ (break) a window in our classroom.
7. We_____haven't decided_________ (not decide) what to get Mark for his birthday yet.
8. I___________have already finished_______ (already/ finish) my homework. It was easy!
9. Jorge ________hasn't played__________ (not play) tennis since his injury.
10. My parents ________have been__________ (be) to Australia three times.