The oldest and hardest cow beef may be made as tender and tasty as young and choice met. ”This declaration was made by the French physicist Denis Papin in book published in 1681, which described his “New Digester” or pressure cooker. It was a cast iron pot with an air-tight lid, which allowed liquids to boil at a higher temperature than usual, and so it cooked food in a quarter of the time. The food was cooked by pressurized steam being forced through it at about 121℃. All pressure cookers were made of cast iron until 1905, when the first aluminum model was made in America. In 1938, Alfred Vischer, a man from Chicago, U. S. A., designed a simple interlocking pan and lid, and an improved pressure-tight seal（密封）—a replaceable rubber sealing ring. When Vischer’s patent（专利）expired in 1954, many companies entered the field, and the rapid pressure cooker became popular with people with people who had little time to cook or had to supply food for unexpected guests. 小题1:From the passage we can learn pressure cooker made of cast iron lasted at least ____years.
a. Denis Papin called his invention “New Digester”. b. It began to be widely used by common families. c. Instead of cast iron, it was first made of aluminum. d. The first pressure cooker was invented in France. e. Alfred Vischer greatly improved its design. f. Vischer’s patent came to an end. g. Many other companies began to produce it.
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