Farmers here keeping the soil rich and diseases.
A. focus on…free of
B. center … free from
C. attend on… free of
D. depend on… free from
网友回答
(答案→)A. focus on…free of
B. center … free from
C. attend on… free of
D. depend on… free from
解析：这题考查词组辨析：focus on专注于，attend on照料depend on依赖，free of 和 free from，免于，没有，句意是：这里的农民专注于保存土壤肥沃并免除疾病。选A。