实际的强度水平取决于诸如大城市的物理布局、人口密度和生产活动之类的因素。

The actual level of intensity depends on such factors as the physical layout, population density, and productive activities of a metropolis.

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物理约束(体积和密度)可能也要求修改机器设备，如汽车和飞机。

Physical constraints (mass and density) may also require modifications in machines such as automobiles and airplanes.

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如果我们从物理意义或者,概率密度的角度来看这个问题，我们需要把波函数平方。

So again if we look at this in terms of its physical interpretation or probability density, what we need to do is square the wave function.

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So again if we look at this in terms of its physical interpretation or probability density, what we need to do is square the wave function.

如果我们从物理意义或者,概率密度的角度来看这个问题，我们需要把波函数平方。

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