Congo, officially the Republic of the Congo or Congo Republic, also known as Congo-Brazzaville is a country located on the western coast of Central …查看更多内容
What American invention, patented in 1794, changed the economy of an entire region, yet it was “so valuable as to be worthless to the inventor”?
答:
After perfecting his cotton gin, Eli Whitney secured a patent (1794), and he and his friend Phineas Miller went into business manufacturing and servicing the new gins...
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