THE AMBER OPEN LIGHT ON THE REFUEL/DEFUEL PANEL:

单选题

THE AMBER OPEN LIGHT ON THE REFUEL/DEFUEL PANEL:

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单选题

WHEN A CARGO HEATING CONTROLLER FAILS, THE:

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材料题

recting a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel,number of wheels teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second. In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second. This is about a million times faster than the speed of an airplane.Objects are visible to the human eye as light is______.

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材料题

red to as the photoelectric effect. This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us to see things around us.3 .Things that give off light are known as sources of light. During the day,the primary source of light is the sun. Other sources of light include s

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材料题

ce the window. The page is in the shadow again, while the bright light is in your eyes. Try sitting with your right side toward the window. This is very well for reading, but if you were writing, the shadow of your hand would fall across the page and bother(打搅) you a little. There is just one other way:sit with your left side to the window. Now everything is perfect for reading and for writing, too. Whatever kind of light is in the room, the rule about the right to sit is always the same. The be

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