2019수능특강 영어 21강 본문

수능특강 영어 21강.hwp

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21강

1

As pretty as the orchids they pollinate, orchid bees come in a brightly colored array of brilliant and metallic blues, greens, and purples. These bees are not social like honeybees—they are typically solitary in nesting, with no division of labor and little communal activity. The males leave the nest shortly after birth and never return, spending their lives collecting flower fragrances that they store in special grooves on their hind legs and that may be released to attract females. Females construct nests from mud, resins, and other materials and gather both nectar and pollen from a variety of plants. The two hundred species of orchid bees are native to Central and South America and play an important role in the pollination of many orchids. Only a single species can be found in the United States. This bee, Euglossa vidrissimia, is a recent arrival from either Mexico or Central America and was likely introduced to the United States accidentally.

 

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A liquid is like a gas in that its molecules move around or ‘flow’ (that’s why both are called ‘fluids’, while solids aren’t). But the molecules in a liquid are much closer to each other than the molecules in a gas. If you put a gas into a sealed tank, it fills every nook and cranny of the tank up to the top. The volume of gas rapidly expands to fill the whole tank. A liquid also fills every nook and cranny, but only up to a certain level. A given amount of liquid, unlike the same amount of gas, keeps a fixed volume, and gravity pulls it downwards, so it fills only as much as it needs of the tank, from the bottom upwards. That’s because the molecules of a liquid stay close to each other. But, unlike those of a solid, they do slide around over each other, which is why a liquid behaves as a fluid.

 

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Before formalized science, some very smart people believed in some really weird things. At about the same time Johann Sebastian Bach was composing symphonies, many scientists asserted that “phlogiston” resided within everything you could burn, and once you set it on fire, the phlogiston escaped into the air. If you had some burning wood in a pot and placed a lid over it, the flame would go out because the air could hold only so much phlogiston before it was saturated. Left in the open, a piece of wood eventually turned to ash and was, as they put it, fully dephlogisticated. This idea lasted for about a hundred years before it was debunked by diligent scientific attacks. Eventually, scientists realized there was no such thing as phlogiston, and the real magic element was oxygen. Flames consumed oxygen, and lids starved flames.

 

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Over the millennia, owls evolved tubular eyes, which face forward and are immovable, and are the reason owls developed the ability to turn their heads 270 degrees. Owl eyes have more black-and-white detecting rods than color cones, allowing them to see in the dark. Their large round yellow eyes, with dark pupils wide enough to let in small amounts of light in darkness, are one of the first things we notice about them. In the human world, large eyes with wide pupils hold a certain attraction both for the viewer and the viewed. Studies show that a person’s pupils dilate in the presence of someone they are attracted to. Advertisers dilate the eyes of models in photographs to make their products more attractive by default. Nature, it seems, has prepared us biologically to be attracted to owls by giving them such big eyes.