Scientists can"t yet make an invisibility cloak (斗篷) like the one that Harry Potter uses. But, for the first time, they"ve constructed a simple cloaking device that makes itself and something placed inside it invisible to microwaves.
When a person "sees" an object, his or her eye senses many different waves of visible light as they bounce off the object. The eye and brain then work together to organize these sensations and reconstruct the object"s original shape. So, to make an object invisible, scientists have to keep waves from bouncing off it. And they have to make sure the object casts no shadow. Otherwise, the absence of reflected light on one side would give the object away.
Invisibility isn"t possible yet with waves of light that the human eye can see. But it is now possible with microwaves. Like visible light, microwaves are a form of radiant energy. They are part of the electromagnetic spectrum (电磁波频谱), which also includes radio waves, infrared light, ultraviolet rays, X rays, and gamma rays. The wavelengths of microwaves are shorter than those of radio waves but longer than those of visible light.
The scientists" new "invisibility device" is the size of a drink coaster and shaped like a ring. The ring is made of a special material with unusual ability. When microwaves (微波) strike the ring, very few bounce off it. Instead, they pass through the ring, which bends the waves all the way around until they reach the opposite side. The waves then return to their original paths.
To a detector set up to receive microwaves on the other side of the ring, it looks as if the waves never changed their paths as if there were no object in the way! So, the ring is effectively invisible.
When the researchers put a small copper loop inside the ring, it, too, is nearly invisible. However, the cloaking device and anything inside it do cast a pale shadow. And the device works only for microwaves, not for visible light or any kind of electromagnetic radiation. So, Harry Potter"s invisibility cloak doesn"t have any real competition yet.
单选题
Harry Potter is mentioned in the passage, because scientists
【正确答案】
C
【答案解析】[解析] 题意：文章中提到哈里·波特，因为科学家们……。
根据文章第一段“Scientists can"t yet make an invisibility cloak like the one that Harry Potter uses ... they"ve constructed a simple cloaking device that makes itself and something placed inside it invisible to microwaves.”可知，科学家们制造了一种隐形装置，可以使装置本身和其中的物体不被微波发现，所以A项、B项和D项都是错误的，唯有C项正确。文章提到哈里·波特的隐形衣是为了引出文章中所述的隐形环。故本题选C。
单选题
What is true of microwaves?
【正确答案】
B
【答案解析】[解析] 题意：关于微波哪项是正确的?
根据文章第三段最后一句“The wavelengths of microwaves are ... longer than those of visible light.”可知微波的波长比可见光长，故A项错误，B项正确。根据本段第三句“Like visible light, microwaves are a form of radiant energy.”可知微波与可见光一样都是一种辐射能，所以C项错误。根据本段第一、二句“Invisibility isn"t possible yet with waves of light that the human eye can see. But it is now possible with microwaves.”和常识都可知道微波是不可见的，所以D项错误。故本题选B。
单选题
What is NOT true of the invisibility device?
【正确答案】
B
【答案解析】[解析] 题意：关于隐形装置哪项不正确?
根据第四段第三句“When microwaves strike the ring, very few bounce off it.”可知，微波到达环表面时，只有极少的微波反射回来，所以B项说法错误，C项说法正确。根据本段第二句“The ring is made of a special material with unusual ability.”可知环由特殊材料制成，所以A项正确。根据本段倒数第二句“they pass through the ring, which bends the waves all the way around until they reach the opposite side”可知微波通过环，发生弯曲并一直抵达环的另一端，所以D项正确。故本题选B。
单选题
What does the word "coaster" mean in the passage?
【正确答案】
A
【答案解析】[解析] 题意：文章中“coaster”这个词是什么意思?
根据第四段第一句“The scientists" new "invisibility device" is the size of a drink coaster and shaped like a ring.”可知隐形装置呈环状，有一个drink coaster那么大。四个选项中很显然B项和D项错误，而A项符合文章所述。coaster意为：沿岸贸易船，杯托，小托盘，过山车等。故本题选A。
单选题
Harry Potter"s invisibility cloak doesn"t have any real competition yet, because
【正确答案】
C
【答案解析】[解析] 题意：哈里·波特的隐形衣目前还没有竞争对手，因为……。
根据最后一段第二、三句“However, the cloaking device and anything inside it do cast a pale shadow. And the device works only for microwaves, not for visible light or any kind of electromagnetic radiation.”可知隐形装置及其内的物体会产生淡淡的阴影，而且隐形效果只见于微波。所以本题选C。