A number of students        trees every year and the number of them        increasing.

“____either you or he to go there?” “_____is.”

---- A number of voiunteers _____ willing to teach in China’s rural areas.----- Yes. The number _____ getting bigger and bigger.

 Every student as well as all the teachers ____ required to be at the bus station at 6:30 tomorrow.

 The writer and professor, whom I often refer to at the meetings, ____ famous for those works.