A.landlords B.tenants C.farmers D.wage laborers
A.Use of artificial fertilizer. B.Introduction of new agricultural machinery. C.The'Open-field'system. D.A system of crop rotation.
A.The open field system provided a good opportunity to experiment. B.The open field system wasted land. C.The open field system was wasteful of labor and time. D.The open field system made livestock farming difficult.