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问题 单项选择题

曝光时间大于0.5s，测量管电流的最佳仪表是

A．V表

B．A表

C．kV表

D．mV表

E．mA表

答案

参考答案：E

解析：曝光时间大于0.5s，测量管电流的最佳仪表是mA表。小于0.5s，mA表指针不能稳定指示；mAs表指示管电流与曝光时间的乘积，本身具有阻尼系统，所以能稳定指示，并保持下来。

单项选择题

She’s cute, no question. Symmetrical features, flawless skin, looks to be 22 years old—entering any meat-market bar, a woman lucky enough to have this face would turn enough heads to stir a breeze. But when Victor Johnston points and clicks, the face on his computer screen changes into a state of superheated, crystallized beauty. "You can see it. It’s just so extraordinary," says Johnston, a professor of biopsychology at New Mexico State University who sounds a little in love with his creation.
The transformation from pretty woman to knee-weakening babe is all the more amazing because the changes wrought by Johnston’s software are, objectively speaking, quite subtle. He created the original face by digitally averaging 16 randomly selected female Caucasian faces. The changing program then exaggerated the ways in which female faces differ from male faces, creating, in humanbeauty-science field, a "hyper-female". The eyes grew a bit larger, the nose narrowed slightly and the lips plumped. These are shifts of just a few millimeters, but experiments in this country and Scotland are suggesting that both males and females find "feminized" versions of averaged faces more beautiful.
Johnston hatched this little movie as part of his ongoing study into why human beings find some people attractive and others homely. He may not have any rock-solid answers yet, but he is far from alone in attempting to apply scientific inquiry to so ambiguous a subject. Around the world, researchers are marching into territory formerly staked out by poets and painters to uncover the underpinnings of human attractiveness.
The research results so far are surprising—and humbling. Numerous studies indicate that human beauty may not be simply in the eye of the beholder or an arbitrary cultural artifact. It may be ancient and universal, wrought through ages of evolution that rewarded reproductive winners and killed off losers. If beauty is not truth, it may be health and fertility: Halle Berry’s flawless skin may fascinate moviegoers because, at some deep level, it persuades us that she is parasite-free.
Human attractiveness research is a relatively young and certainly contentious field—the allure of hyper-females, for example, is still hotly debated—but those on its front lines agree on one point: We won’t conquer "looks-ism" until we understand its source. As psychologist Nancy Etcoff puts it: "The idea that beauty is unimportant or a cultural construct is the real beauty myth. We have to understand beauty, or we will always be enslaved by it. \

The word "symmetrical" underlined in Paragraph 1 is closest in meaning to ______.

A．proportionate

B．gorgeous

C．splendid

D．unique
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单项选择题

关于脓疱型银屑病不正确的是（）

A.可伴高热、寒战

B.皮疹成批出现

C.四肢屈侧更易受累

D.脓疱可融合成脓湖

E.不会转化为红皮病
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