Ultraviolet light from the sun changes a substance in the skin into vitamin D.
VOA: special.2009.04.21
If you get some of these in the upper atmosphere, a photon, an ultraviolet photon, has the energy capable of breaking this bond.
如果你把它放到大气层上,一个光子,一个紫外光光子,有能量可以破坏它的化学键。
If you get some of these in the upper atmosphere, a photon, an ultraviolet photon, has the energy capable of breaking this bond.
如果你把它放到大气层上,一个光子,一个紫外光光子,有能量可以破坏它的化学键。
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