The number of teachers in this school（) unknown.A. areB. is beingC. isD. are being

The annual income of school teachers in this place

However, at times this balance in nature is _____, resulting in a number of possible unfor

There is a fall in the number of students who take this major.A.decreaseB.riseC.topD.incr

The number of books in this library has been increasing considerably in the past two years

This morning in the class our teacher lost his _

In the first class in this semester the teacher started ______ a story she experienced during the summer holiday.