unit area

基本解释

It should be a pressure which is a force per unit area.
它应该等于压强,或者说是单位面积上的受力。
The density for a flat object would be the mass per unit area.
一个平面物体的密度是每单位面积元的质量。
The other way to think about it is divergence is the source rate, it is the amount of fluid that is being inserted into the system, that is being pumped into the system per unit time per unit area.
另外一个理解方法是，散度是源头的“冒出率”,它是流体往系统输入的量，也就是单位时间内，单位面积新冒出的流体。

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Last month Hanoi also dispatched 1, 200 members of an elite police unit to the area.
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