As on the Moon, the extent of large impact cratering (i.e. craters too big to have been filled in by erosion since they were formed) serves as an age indicator for the Martian surface.

与月球上相同，那些巨大陨石坑的范围（例如，那些巨大到自形成后尚未被尘埃填满的陨石坑）标志着火星表面的年龄。

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As on the Moon, the extent of large impact cratering serves as an age indicator for the Martian surface.

和在月球的一样，大型撞击陨石坑的范围之广可以显示出火星表面的年龄。

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Because calculations and lab experiments replicating the Venusian surface and atmosphere show that emissivity decreases over time, emissivity can be an important indicator of a substance's age.

同时因为计算与实验室的实验复制的金星地表与大气层的活动，表明辐射率一直在下降，所以辐射率能够成为某个地质年代的一个重要指标。

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On the surface that seems to make sense, but history shows that employment is a lagging indicator, one of the last areas to begin improving in an economic recovery.

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On the surface that may not seem like a positive for HP but it's an important indicator of where spending is headed and at some level helps validate HP's purchase of Compaq.

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