2. 外语
  3. The camera is often thought to be a modem invention. But as early 1727, a German physicist 【B1】______ that light darkens silver

The camera is often thought to be a modem invention. But as early 1727, a German physicist 【B1】______ that light darkens silver

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问题     The camera is often thought to be a modem invention. But as early 1727, a German physicist 【B1】______ that light darkens silver salt in a chemical 【B2】______ . Using a camera, a big box with a small hole to let the light in, he made 【B3】______ images on the salt. Silver salt is still the 【B4】______ of film today. Then a French scientist made the first 【B5】______ picture by using a special 【B6】______ of metal sensitized with silver salt. A photography he made in 1826 still 【B7】______ . The painter, Daguerre improved on the process 【B8】______ placing common salt the kind we eat on the metal. This was in 1839, 【B9】______ , but the problem was the printing of photographs, and it wasn’t until other scientists developed the kind of paper we now use, that good printing was possible and photograph become truly modem. In 1860, Matthew Bradey was able to take his famous pictures of the American Civil War, 【B10】______ . In the 20th century, George Eastman of the United States simplified film developing, and Dr. Edwin Land invented the so-called "instant" camera with self developing film. 【B11】______ it has taken more than one hundred years for the camera to reach its present condition of technical refinement.
【B2】
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