6. The graduating class
___________research work on the issue for several weeks.
(has done, have done, had done, will have done)
7. The drugstore__________
by midnight.
(has closed, have closed, had closed, will have closed)
8. Scientists____________
research and experiments to see how the Philippine eagle
could be saved.
(has conducted, have conducted, had conducted, will have conducted)
9. Many children_____________
to the park for the music festival.
(has gone, have gone, had gone, will have gone)​