As a way of reconciling these two facts, scientists have hypothesized that nearly all of the oxygen being produced was taken up by iron on Earth's surface.

为了调和这两个事实，科学家们假设，几乎所有产生的氧气都被地球表面的铁吸收了。

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The color changes are executed by two different kinds of cells in the octopus' skin, mainly by color cells on the skin's surface call chromatophores.

颜色的变化是由章鱼皮肤上的两种不同的细胞造成的，主要是皮肤表面的色素细胞。

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It recommended using geometric lines of latitude and longitude to convey a three-dimensional Earth on a two-dimensional surface, and it included the co-ordinates of over 8, 000 locations in the ancient world.

ECONOMIST: There is no such thing as an objective map

Picture what it would be like to roll a bowling ball onto the two-dimensional surface of a trampoline.

NPR: Einstein: Relatively Speaking, a Complicated Life

They flew on two suborbital and four Earth-orbital Mercury launches, nine Earth-orbital Gemini flights, two Earth-orbital Apollo tests, and two lunar-orbital tests that made those lunar surface landings possible.

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