However, due to a considerable variation in land area, 1 population density and climatic, geological and topographical conditions, the extent of forest cover differs greatly among the island states.

然而，由于各岛屿国家的陆地面积、1人口密度、气候、地理地形条件等有很大差异，它们的森林覆盖程度也有很大差别。

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At the other end of the list are cities in Canada and the United States, which benefit from lower population density, favorable climates and stricter air pollution regulation.

污染最轻的是美国和加拿大的城市，原因是它们的人口密度低，气候怡人，并且空气污染管理规定非常严格。

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The simulation of total energy flow and the density of states show that the dodecagonal QPC has photonic gap for TM polarized electromagnetic waves.

能流和态密度的计算结果都表示十二重准晶光子晶体具有光子带隙。

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Another factor may be the impact of density, which, Cox demonstrates, tends to depress fertility rates not only here in the United States, but through much of the world.

FORBES: America's Baby Boom And Baby Bust Cities