2014年4月托福考试模拟试卷及答案(第一套)_第2页

　　Cold storage, or refrigeration, is keeping food at temperatures between 32 and 45 degrees F in order to delay the growth of microorganisms—bacteria, molds, and veast—that cause food to spoil. Refrigeration produces few changes in food, so meats, fish, eggs, milk, fruits, and vegetables keep their original flavor, color, and nutrition. Before artificial refrigeration was invented, people stored perishable food with ice or snow to lengthen its storage time. Preserving food by keeping it in an ice—filled pit is a 4,000-year-old art. Cold storage areas were built in basements, cellars, or caves, lined with wood or straw, and packed with ice. The ice was transported from mountains, or harvested from local lakes or rivers, and delivered in large blocks to homes and businesses.

　　Artificial refrigeration is the process of removing heat from a substance, container, or enclosed area, to lower its temperature. The heat is moved from the inside of the container to the outside. A refrigerator uses the evaporation of a volatile liquid, or refrigerant, to absorb heat. In most types of refrigerators, the refrigerant is compressed, pumped through a pipe, and allowed to vaporize. As the liquid turns to vapor, it loses heat and gets colder because the molecules of vapor use energy to leave the liquid. The molecules left behind have less energy and so the liquid becomes colder. Thus, the air inside the refrigerator is chilled.

　　Scientists and inventors from around the world developed artificial refrigeration during the eighteenth and nineteenth centuries. William Cullen demonstrated artificial refrigeration in Scotland in l748, when he let ethyl ether boil into a partial vacuum. In l805, American inventor Oliver Evans designed the first refrigeration machine that used vapor instead of liquid. In l842, physician John Gorrie used Evans’s design to create an air-cooling apparatus to treat yellow—fever patients in a Florida hospital. Gorrie later left his medical practice and

　　liquid.

　　When kinetic energy is changed to heat energy, liquid molecules turn into vapor molecules.

　　During evaporation, the vapor molecules use energy, and the liquid becomes colder.

　　6. According to the passage, who was the first person to use artificial refrigeration for a practical purpose?

　　William Cullen

　　Oliver Evans

　　John Gorrie

　　Adolphus Busch

　　7. The word it in paragraph 3 refers to

　　printer

　　refrigerator

　　type

　　ether

　　8. Why does the author discuss the brewing industry in paragraph 4?

　　To compare cave storage with mechanical refrigeration

　　To describe the unique problems that brewers faced

　　To praise the accomplishments of a prominent brewer

　　To show how refrigeration changed a whole industry

　　9. The word constrained in paragraph 4 is closest in meaning to

　　restricted

　　spoiled

　　improved

　　alternated

　　10. According to the passage, the first refrigerated railcar used what material as a cooling agent?

　　Ether

　　Ice

　　Ammonia

　　CFCs