States had at least three social levels, usually, an upper class of rulers, a middleclass comprised of managers and merchants, and a lower class of crop producers and agricultural laborers.
国家中至少有三种社会阶层，上层阶级（执政），中产阶级（商人，管理者）和下层阶级（农民，工人）。
Because of the erratic rainfall patterns in Australia, it is often considered that soil moisture sets the upper limit on crop yield potential.
由于澳大利亚降雨类型多变，人们常认为土壤水分给作物产量定了上限。
Practising intensive farming and loosening upper soil layer could hold rainfall water and make it penetrate into soil effectively, which could improve soil quality and crop moisture condition.
精耕细作、疏松表层、保持水土、充分接纳雨水就地入渗增大土壤水库贮水，可有效地改善农田土壤和作物水分条件。
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