单选题 Over-cultivation and a long period of erosion has reduced the ______ of much of the country's farmland.
  • A.sufficiency
  • B.fertility
  • C.prosperity
  • D.mobility
【正确答案】 B
【答案解析】[解析] 各项的意思是：sufficiency“充足”；fertility“肥力”；prosperity“幸运，繁荣”；mobility“活动性，迁移率”。根据句意判断，答案为B。