By the mid-nineteenth century, the term 'icebox' had entered the American language, but ice was still only beginning to affect the diet of ordinary citizens in the United States. The ice trade grew with the growth of cities. Ice was used in hotels, taverns, and hospitals, and by some forward-looking city dealers in fresh meat, fresh fish, and butter. After the Civil War (1861-1865),as ice was used to refrigerate freight cars, it also came into household use. Even before 1880, half the ice sold in New York, Philadelphia, and Baltimore, and one-third of that sold in Boston and Chicago, went to families for their own use. This had become possible because a new household convenience, the icebox, a precursor of the modern refrigerator, had been invented. Making an efficient icebox was not as easy as we might now suppose. In the early nineteenth century, the knowledge of the physics of heat, which was essential to a science of refrigeration, was rudimentary. The commonsense notion that the best icebox was one that prevented the ice from melting was of course mistaken, for it was the melting of the ice that performed the cooling. Nevertheless, early efforts to economize ice included wrapping the ice in blankets, which kept the ice from doing its. Not until near the end of the nineteenth century did inventors achieve the delicate balance of insulation and circulation needed for an efficient icebox. But as early as 1803, an ingenious Maryland farmer, Thomas Moore, had been on the right track. He owned a farm about twenty miles outside the city of Washington, for which the village of Georgetownwas the market center. When he used an icebox of his own design to transport his butter to market, he found that customers would pass up the rapidly melting stuff in the tubs of his competitors to pay a premium price for his butter, still fresh and hard in neat, one-pound bricks.One advantage of is icebox, Moore explained, was that farmers would no longer have to travel to market at night in order to keep their produce cool. What does the passage mainly discuss?A.The influence of ice on the diet B.The development of refrigeration C.The transportation of goods to market D.Sources of ice in the nineteenth century According to the passage , when did the word 'icebox' become part of the language of the United States?A.in 1803 B.sometime before 1850 C.during the civil war D.near the end of the nineteenth century According to the passage , which of the following was an obstacle to the development of theicebox?A.Competition among the owners of refrigerated freight cars B.The lack of a network for the distribution of ice C.The use of insufficient insulation D.Inadequate understanding of physics The author mentions fish in line 4 becauseA.many fish dealers also sold ice B.fish was shipped in refrigerated freight cars C.fish dealers were among the early commercial users of ice D.fish was not part of the ordinary person's diet before the invention of the icebox The word 'it' in line 5 refers toA.fresh meat B.the Civil War C.ice D.a refrigerator The word 'rudimentary' in line 12 is closest in meaning toA.growing B.undeveloped C.necessary D.uninteresting The author describes Thomas Moore as having been 'on the right track' (lines 18-19) toindicate thatA.the road to the market passed close to Moore's farm B.Moore was an honest merchant C.Moore was a prosperous farmer D.Moore's design was fairly successful The 'produce' mentioned in line 25 could includeA.iceboxes B.butter C.ice D.markets The phrase 'forward-look-ing' in line 4 is closest in meaning toA.progressive B.popular C.thrifty D.well-established According to the information in the second paragraph, an ideal icebox wouldA.completely prevent ice from melting B.stop air from circulating C.allow ice to melt slowly D.use blankets to conserve ice According to the passage , Moore's icebox allowed him toA.charge more for his butter B.travel to market at night C.manufacture butter more quickly D.produce ice all year round