📁 黑色Holes
This category is dedicated to sites about black holes - ultra-compact astronomical objects that are predicted by Einstein's theory of general relativity, whose gravity is so strong that not even light can escape.
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Louisa May Alcott Electronic Text from University of Pennsylvania
http://digital.library.upenn.edu/webbin/book/search?author=Louisa+May+Alcott&amode=words&title=&tmode=words