問題詳情

(II)In 2014, the Noble Prize for Physics was awarded to the three Japanese scientistswho invented blue LEDs some 20 years ago. By doing so, they helped to trulyrevolutionize illumination technology. Prior to their invention, red and green LEDshad existed for nearly a third of a century. However, early researchers were unable tobring blue LEDs into the fold until the Japanese scientists came up with their monumental breakthrough.   Having access to blue LEDs was extremely vital, because red, green, and blueLEDs are combined in order to produce the white light that is required to illuminate our world. The invention of blue LEDs made it inevitable that the 21st century would be lit up by LED lamps. The term LED is short for light-emitting diode and refers to devices that emit light when electric currents pass through them. The first LED was created by American engineer Nick Holonyak in 1962, but it was only able to emit a low-intensity red light. Over years, LED technology evolved and has enabled electronic manufactures to use these lights in devices such as cellphones, watches,flashlights, and display screens.   Compared with ordinary light bulbs, LEDs have several benefits. They help toreduce power costs because they are more energy efficient. Also, LEDs have theability to last thousands of hours longer than traditional lighting sources. Unlikefluorescent bulbs, LEDs contain no mercury, a substance that can be hazardous topeople’s health. The only major disadvantage concerning LEDs is that they are stillmore expensive to purchase than older lighting technologies. However, when youfactor in the total cost of ownership, LED lights are actually cheaper due to theirlongevity. So the next time you flick on an LED light, remember to appreciate thisamazing technology that brightens up your day.
4. What is this article mainly about?
(A) A brief history of how the Nobel Prize came out.
(B) Some background information on a useful invention.
(C) An explanation of how light affects our ability to see things.
(D) The reasons why people should frequently change light bulbs.

參考答案

答案：B
難度：適中0.631579
統計：A(1),B(12),C(3),D(2),E(0)

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