15. Researchers _______ to develop vaccines and this will probably take several months to complete.
With the guide _______ the way, we finally got to the village which we were looking for.
I was about to go to bed _____ one of my old classmates made a call to me.
Mr King, _____ legs were badly hurt, was quickly taken to hospital.
He was generally _________ to be the finest poet in the land.
Students are encouraged to _________ the design competition for robots at the university.