Since ancient times people have found various ways to preserve meat.

单选题That performance was pretty impressive.

单选题She read a poem which depicts the splendor of the sunset.

单选题Will you please call my husband as soon as possible?

单选题共用题干 第三篇<br><br>Ways to Create Colors in a Photograph<br><br>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.<br>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(a purplish pink);green and blue mix to produce cyan(a bluish green).When equal parts of all three of these primary-colored beams of light overlap（重叠）,the mixture appears white to the eye.<br>In the subtractive process colors are produced when dye（染料）absorbs some wavelengths and so passes on only part of the spectrum.The subtractive primaries are cyan,magenta and yellow; these primaries or dyes 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.<br>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.

单选题The governor gave a rather vague outline of his tax plan.

单选题The police arrested the suspect yesterday and released him this morning.

单选题共用题干 Vision<br><br>Human vision like that of other primates（灵长目）has evolved in an arboreal（丛林）environment.______(46)<br>In the course of evolution,members of the primate line have acquired large eyes while the nose has shrunk.______ (47) Of mammals（哺乳动物）only humans and some primates enjoy color vision.______(48)Horses live in a single-color world.<br>Light visible to human eyes,however,occupies only a very narrow band in the whole electromagnetic spectrum（光谱）.Ultraviolet rays（紫外线）are invisible to humans though ants and honeybees are sensitive to them.______(49)The world would look terribly different if human eyes were、 sensitive to infrared radiation（红外线）.Then instead of the darkness of night,we would be able to move easily in a strange shadowless world.______(50)<br>But human eyes excel in other ways. They are in fact remarkably discerning in color gradation. The color sensitivity of normal human vision is rarely surpassed even by complicated technical devices.

单选题The book took ten years of thorough research.

单选题John is crazy about pop music.

单选题Jess likes playing basketball，but I like swimming.