来源:http://www.eduzhai.net/gushi/454/gushi_164215.html家鸡的祖先是野生的,那时,它们也会飞,自从人类把它们当做家禽来饲养后,经过训养,鸡的翅膀退化 ...
Wednesday, April 7, 2010
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来源:http://www.eduzhai.net/gushi/454/gushi_164215.html家鸡的祖先是野生的,那时,它们也会飞,自从人类把它们当做家禽来饲养后,经过训养,鸡的翅膀退化 ...
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