Over the centuries, scientists have offered four distinct hypotheses to explain the phenomenon. There is the original “tuck and turn” model, in which the cat pulls in one set of paws so it can rotate different sections of its body. Nineteenth-century physicist James Clerk Maxwell offered a “falling figure skater” explanation, whereby the cat tweaks its angular momentum by pulling in or extending its paws as needed. Then there is the “bend and twist,” in which the cat bends at the waist to counter-rotate the two segments of its body. Finally, there is the “propeller tail,” in which the cat can reverse its body’s rotation by rotating its tail in one direction like a propeller.
这种“踩线”的无力感，令人憋闷，也值得理解。
。whatsapp对此有专业解读
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filter takes a predicate closure and returns a new array containing only the elements for which the predicate returns true.