2. 外语
  3. There are two ways to create colors in a photograph. One method, called additive, starts with three basic colors and adds them t

There are two ways to create colors in a photograph. One method, called additive, starts with three basic colors and adds them t

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问题     There are two ways to create colors in a photograph. One method, called additive, starts with three basic colors and adds them together to produce some other color. The second method, called subtractive, starts with white light(a mixture of all colors in the spectrum)and, by taking away some or all other colors, leaves the one desired.
    In the additive method, separate colored lights combine to produce various other colors. The three additive primary colors are green, red and blue(each providing about one third of the wavelengths in the total spectrum). Mixed in varying proportions, they can produce all colors. Green and red light mix to produce yellow; red and blue light mix to produce magenta; green and blue mix to produce cyan. When equal parts of all three of these primary-colored beams of light overlap, the mixture appears white to the eye.
    In the subtractive process colors are produced when dye(as in paint or color photographic materials)absorbs some wavelengths and so passes on only part of the spectrum. The subtractive primaries are cyan(a bluish green), magenta(a purplish pink)and yellow; these additive primaries or dyes that absorb red, green and blue wavelengths respectively, thus subtracting them from white light. These dye colors are the complementary colors to the three additive primaries of red, green, and blue. Properly combined, the subtractive primaries can absorb all colors of light, producing black. But, mixed in varying proportions, they too can produce any color in the spectrum.
    Whether a particular color is obtained by adding colored lights together or by subtracting some light from the total spectrum. The result looks the same to the eye. The additive process was employed for early color photography. But the subtractive method, while requiring complex chemical techniques, has turned out to be more practical and is the basis of all modern color films.
How is the passage organized?
选项 A、The reasons for a choice are explained in depth.
B、A general statement is justified by a series of historical examples.
C、Two basic causes are compared.
D、Related processes are described one after the other.
答案C
解析 文章结构题。文章从使照片具有色彩的两种方法，加色法和减色法开头，接着分别介绍两种色法的基本原理，最后对比了两种色法，故答案为C。原文并没有对两种色法作depth解释，选项A不正确；原文没有提及historical examples，故选项B不正确；原文不是对processes的描述，选项D也不正确。
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