Owls are equipped with highly developed stealth（隱形；隱身）technology that helps them charge towards prey—an animal hunted and eaten by another animal，a study has shown.
Owls have flight feathers that absorb aerodynamic（空氣動力學的）sound and control the vibrations that occur when a bird beats its wings.The result is perfect silence as it approaches a mouse or other prey.
Scientists used lasers and high-speed cameras to analyze and compare long-eared owl，eagle and pigeon feathers during flight.While differing in size，all three kinds of birds have a similar wing-beat style.Professor Jinkui Cha led the research.He said，"Many owls have a unique and fascinating ability to fly so silently that they are out of their prey's hearing range，duo to their feather structure.This behaviour has long been of interest to engineers，as we seek to apply the owls' noise-reduction mechanisms（機制） to other purposes and situations that benefit society.
"Now，however，we know the owls' silent flight ability is even better than we thought.Of all birds the owl is the king of acoustic stealth.It manages to prevent not only the aerodynamic noise.jye.ai the ow's are gliding，but also the mechanical noise caused by vibrations during flying."
He added，"This is remarkable，considering the sudden jumping，bending and twisting the wings are subjected to the noise that is created by other birds.In the scientific world，the process used to remove this mechanical noise is called damping skill，which means the removal of mechanical energy from a vibrating system usually by changing it into best and allowing it to remain study.Our research showed the long-cared owl has amazing damping skill，meaning it can remain amazingly stable and remove the mechanical noise caused by the movement of its feathers—quite an impressive achievement of engineering.This study will hopefully provide a further insight into the owls' silent flight mechanism and help engineers develop ideas for special materials or structures，such as onshore wind ships，where similar noise removal can be applied."
（1）What can we learn about owls according to the passage？ BB
A．They are active during the day.
B．They attract match attention of engineers.
C．They have similar wings to eagles.
D．They beat wings without vibrations.
（2）According to Jinkui Chu's words in Paragraph 4，we can know that DD .
A．owls are good at capturing prey.
B．owls have a good sense of hearing
C．owls are good at jumping and twisting
D．owls have silent flight ability
（3）What does the underlined word"it"in Paragraph 5 refer to？ CC
A．The mechanical noise.
B．The vibrating system.
C．Mechanical energy.
D．The removal of mechanical energy.
（4）What is mainly talked about in this passage？ DD
A．Facts about stealth technology.
B．Technique that owls use to fly.
C．The reason for researching into owls.
D．A study about owls' unique ability.
【答案】B；D；C；D
【解答】
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發(fā)布：2024/4/20 14:35:0組卷：0引用：1難度：0.5
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