题型:阅读理解 题类:模拟题 难易度:普通
安徽省六安市第一中学2016-2017学年高三下学期英语高考模拟考试试卷
Hummingbirds(蜂鸟) are one of nature's most energetic fliers and the only birds to hover(盘旋) in the air by relying on their strength alone.
Now scientists have found that it is the ratio(比值) of the bird's wing length to its width that makes them so efficient. The discovery is helping experts compete with 42 million years of natural selection to build helicopters that are increasingly efficient.
David Lentink, an assistant professor at Stanford University in California, tested wings from 12 different species of hummingbirds, which he sourced from museums. He placed them on a machine used to test the aerodynamics(气力学) of the helicopter blades(桨叶). Professor Lentink's team used the same machine to test the blades from an advanced micro-helicopter used by the UK's army. They found that the micro-helicopter's blades are as efficient at hovering as the average hummingbirds.
But while the micro-helicopter's blades kept pace with the average hummingbird wings, they could not keep up with the most efficient hummingbird's wing. The wings of Anna's hummingbird were found to be about 27 percent more efficient than the man-made micro- helicopter's blades.
While Professor Lentink wasn't surprised at nature's superiority, he said that helicopter blades have come a long way. “The technology is at the level of an average hummingbird,” he said. “A helicopter is really the most efficient hovering device that we can build. The best hummingbirds are still better, but I think it's amazing that we're getting closer. It's not easy to match their performance, but if we build better wings with better shapes, we might match hummingbirds.”
Professor Lentink said that we don't know how hummingbirds maintain their flight in a strong wind, how they navigate(确定方向) through branches, or how they change direction so quickly. He thinks that great steps could be made by studying wing aspect ratios-the ratio of wing length to wing width. Understanding these abilities and characteristics could be a benefit for robotics and will be the focus of future experiments.
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①Tested wings from different species of hummingbirds
②Got resources from museums
③Analyzed the results and drew a conclusion
④Tested the blades from a micro-helicopter
Shakespeare's Birthplace and Exhibition of Shakespeare's World. Welcome to the world-famous house where William Shakespeare was born in 1564 and where he grew up. The property(房产) remained in the ownership of Shakespeare's family until 1806. The House has welcomed visitors travelling from all over the world,for over 250 years.
OPENING TIMES 20 Mar to 19 Oct Mon to Sat:9:00 am to 5:00 pm Sun:9:30 am to 5:00 pm 20 Oct to 19 Mar Mon to Sat:9:30 am to 4:00 pm Sun:10:00 am to 4:00 pm |
◆Enter through the Visitors' Centre and see the highly-praised exhibition Shakespeare's World, a lively and full introduction to the life and work of Shakespeare.
◆Stand in the rooms where Shakespeare grew up.
◆Discover examples of furniture and needlework from Shakespeare's period.
◆Enjoy the traditional(传统的) English garden, planted with trees and flowers mentioned in the poet's works.
ADMISSION: Adult £4.90 Child £2.20 Family £12.00 (2 adults + up to 3 children) |
The Birthplace is within easy walking distance of all the car parks shown on the map;nearest is Windsor Street(3 minutes' walk).
The House may present difficulties but the Visitors' Centre, its exhibition, and the garden are accessible(可进入的) to wheelchair users.
The Shakespeare Coffee House(opposite the Birthplace).
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