對於現代的人，尤其是城市的人來說，炎炎夏季，如果沒有冰箱該是多麼可怕的事情。下面，我們就一起來看一篇公共英語三級閱讀文章，瞭解一下冰箱的起源吧。
The Origin of Refrigerators
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 job. 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 Georgetown was 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 his icebox, more explained, was that farmers would no longer have to travel to market at night in order to keep their produce cool.
冰箱的由來
直到19 世紀中期，"冰箱"這個名詞才進入了美國語言，但冰僅僅只是開始影響美國普通市民的飲食。冰的買賣隨着城市的發展而發展。冰被用在旅館、酒館、醫院以及被一些有眼光的城市商人用於肉、魚和黃油的保鮮。內戰(1861-1865)之後，冰被用於冷藏貨車，同時也進入了民用。甚至在1880 年前，半數在紐約、費城和巴爾的摩銷售的冰，三分之一在波士頓和芝加哥銷售的冰進入家庭使用，因爲一種新的家庭設備，冰箱，即現代冰箱的前身，被髮明瞭。
製造一臺有效率的冰箱不像我們想象的那麼簡單。19 世紀早期，關於對冷藏科學至關重要的熱物理知識是很淺陋的。認爲最好的冰箱應該防止冰的融化這樣一個普遍的觀點顯然是錯誤的，因爲正是冰的融化起了製冷作用。早期爲節省冰的努力，包括用毯子把冰包起來，使得冰不能發揮它的作用。直到近19 世紀末，發明家們才成功地找到有效率的冰箱所需要的精確的隔熱和循環的精確平衡。
但早在 1803 年，一位有發明天才的馬里蘭農場主，托馬斯·莫爾，找到了正確方法。他擁有一個農場，離華盛頓約 20 英里，那裏的喬治鎮村莊是集市中心。當他用自己設計的冰箱運送黃油去市場時，他發現顧客們 會走過裝在競爭者桶裏那些迅速融化的黃油而給他比市價更高的價格買他仍然新鮮堅硬，整齊地切成一磅一塊的黃油。莫爾說他的冰箱的一個好處是使得農民們不必在夜裏上路去市場以保持他們產品的低溫。更高的價格買他仍然新鮮堅硬，整齊地切成一磅一塊的黃油。莫爾說他的冰箱的一個好處是使得農民們不必在夜裏上路去市 場以保持他們產品的低溫。
附：公共英語三級閱讀技巧
如何做原因性的題目
由於閱讀理解的文章絕大多數是屬於說明文體裁，而說明文的主要功能是對事物、現象的解釋和闡述。因此許多題目都涉及到分析和辨別事物的原因或成因。例如：
The main reason for the failure of the organization to achieve the success is that _____.
Mouthwashes are not effective cure for bad breath mainly BECause _________.
Which of the following is mentioned as one of the causes for the earthquake ______.
在做尋找事物原因的題目時，有幾點要特別注意。
1.問的是主要原因或真正原因，而命題人員總把一些次要的`，非直接的，非根本的原因放進選項。由於這些次要的原因也是文章中提到的，因此考生如不仔細，往往會把次要原因當作答案。
這就告訴我們，做這類題目，首先要注意問題中的the main/chief/real cause (reason，factor) 這些詞，提醒自己，問題問的是主要原因。然後分析事物的諸多的原因，理出最主要的，直接的，根本的原因。
2.問的是事物的原因，但出現在選項裏的還有事物的後果、影響。由子這些後果、影響和原因一樣，都是指一件事，且都出現在同一相關段，或相關句中，稍不留心，就會搞錯。
這就告訴我們，做尋找原因的題目時，對文章所說的事物的原因、結果、影響，應理清它們之間的邏輯關係。不要錯把結果當原因。
