of the ice that performed the cooling. Early efforts to save ice included wrapping up the ice in blankets, which kept the ice from doing its job. Not until near the end of the nineteenth century did inventors achieve the delicate balance needed for an efficient icebox.

　　But as early as 1803, a Maryland farmer, Thomas Moore, had been in the correct direction. He owned a farm and used an icebox of his own design for the transportation of his butter to a market in the village of Georgetown. And there he found that customers would pass up the rapidly melting goods of his competitors, but to pay a higher price for his butter, still fresh and hard in neat, one­pound bricks. One advantage of his icebox, Moore explained, was that farmers would no longer have to travel to market at night in order to keep their produce cool. As a result, Moore managed to earn a large sum of money.

　　The Origin of Refrigerators

　　History of the icebox By the mid­19th century, the (1)____ that ice had on American citizens'

　　life was limited mainly to the diet.

　　When cities grew, the ice (2)____ increased.

　　Forward­looking businessmen used ice to keep meat, fish and butter (3)____．

　　After the Civil War, ice also came into (4)____ use.

　　Incorrect (5)____

　　about the icebox The icebox (6)____ best when the ice was prevented from melting.

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