听力原文: Today I will be talking about the invention of the camera and photography.
Camera is often thought to be a modern invention. But as early as 1727, a German physicist discovered light darkened silver salt, a chemical compound. Using as a camera, a big box with a small hole to let the light in, he made temporary images on the salt. Silver salt is still the basic film today. Then a French scientist made the first permanent picture by using a special piece of metal sensitized with silver salt. A photograph he made in 1826 still exists.
The painter DeGair improved on the process by placing common salt, the kind we eat, on the metal. This was in 1839, the official date of the beginning of photography. But the problem was the printing of the photo- graphs. And it was not until other scientists developed the kind of paper we now use that good printing was possible, and photography became truly modern.
In the 1860's, Mathew Brady was able to take his famous pictures of the American Civil War, thus making portrait poses very popular. In the 20th century, George Eastman of the United States simplified film developing, and Edwin Land invented the so-called instant camera with self-developing film.
If we say photography came into existence in 1839, it follows that it has taken more than 100 years for the camera to reach its present condition of technical refinement.
The first permanent picture was made by using_________
A.special paper
B.silver salt
C.common salt
D.a special metal
第7题
A.1号线一期提供专用UPS
B.1号线续建、2、5号线不提供专用UPS采用集中UPS供电方式
C.1号线一期、2号线没有进行分时间管理
D.1号线续建、5号线分1分钟和15分钟UPS供电管理工作
E.3号线分5分钟和30分钟UPS供电管理工作
第8题
A.客服中心
B.AFC机房
C.售票机房
D.弱电机械室
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