As geologists, we examine layers of sediment on the Earth' ssurface to approximate the dates of past geologic time periods.
作为地质学家,我们研究地球表面的沉积层以估算过去地质时期的年代。
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The scene of the Five Starred Red Flag against the dark sky on the grey lunar surface was taken by a camera on the Chang'e s robotic probe's lander and then sent to the ground control.