But need to note is a hardness up, its toughness is to catch up, this can be a good iron manhole cover.

但需要注意一点就是硬度跟上了，其韧性也要跟上，这样才能算是好的铸铁井盖。

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Cover crops can improve the water holding ability of soil; however, its effect on soil hardness depends on the moisture content of soil.

覆盖作物可改善土壤持水能力，但是对土壤硬度的影响与土壤含水率有关。

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Cast iron manhole cover of good quality is to see its toughness and hardness.

质量好的铸铁井盖是要看其韧度和硬度的。

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