上图：液晶微滴层层叠加成的三维体可能对穿透它的光线产生全新而有价值的影响。NASA授权图片。
Above: 3-dimensional stacked layers of liquid crystal droplets could have some novel and useful effects on light that passes through them. Image courtesy NASA.
Flickr Creative Commons是一个非常优秀的寻找图片的地方，而且因为有授权，你可以重复使用。
Is a great place to look for images you can freely reuse with attribution.
纪念品上的图片都是经过授权的。
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