一个平面物体的密度是每单位面积元的质量。

The density for a flat object would be the mass per unit area.

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那意味着每单位面积的产量增加了超过6%。

That means the production increases more than 6 percent per unit of area.

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例如，TDR的使用可能允许在住宅单位，每单位面积和建筑面积比例的增加数量的增加。

For example, the use of TDR may allow for increases in the number of dwelling units per unit area and increases in floor area ratios.

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