Заполните пропуски соответствующей формой глагола to be.
1) The students........in the reading hall before the lessons.
2) the lesson.... ..... over in 5 minuters.
3) the data of the land productivity ..... quite necessary to determine the rate of taxation and for proper land use management.
4)Land.....a limited resource and the misuse of land to such problem as non - sustainable land use.