单项选择题
A.土壤孔隙直径在0.002~0.2mm之间B.土壤孔隙直径大于0.1mmC.土壤孔隙直径小于0.001mmD.土壤孔隙直径小于0.002mm
A.碳B.铁C.硫D.镁
A.沙土B.壤土C.黏土D.湿土