Farmers here _________keeping the soil rich and _________diseases.A.focus on…free ofB.center … free fromC.attend on… free ofD.depend on… free from
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A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。