Bendable wings covered with overlapping (重疊部分) pieces looking like fish scales could be used to build more controllable, fuel?efficient aircraft, a new study finds.

Nowadays, conventional aircraft typically rely on ailerons (副翼) to help control the way the planes tilt (傾斜) as they fly. However, when the Wright brothers flew the first airplane, Flyer 1, over a century ago, they used no ailerons but wires that pulled and stretched the wood?and?canvas wings, to control the plane.

“Scientists have long sought to develop aircraft that can change their wings during flight, just as birds can. However, most previous attempts have failed because they relied on heavy mechanical control structures within the wings. These structures were also complex and unreliable，” said Neil Gershenfeld, a physicist and director of the Centre for Bits and Atoms at MIT.

The new wing consists of a system of tiny, strong and lightweight modules (組件). The shape of the wing can be changed uniformly along its length using two small motors, which apply a twisting pressure to each wingtip. These wings are covered in “skins” of overlapping strips of flexible material like fish scales. These strips move across each other as the wings change themselves, providing a smooth outer surface, the researchers explained.

Wind tunnel tests of these wings showed that they at least matched the aerodynamic (氣動(dòng)) properties of conventional wings, at about one?tenth the weight. “Initial tests using remotely piloted aircraft made with these wings have shown great promise，” said Benjamin Jenett, a graduate student at the Centre for Bits and Atoms at MIT.

The new modular structures the scientists developed could be manufactured quickly in mass quantities and then installed by teams of small robots. These modular structures also can be disassembled more easily, making repairs simpler.

“Still, the first aircraft built using this strategy will not be a passenger jet，” Gershenfeld said. “Instead, the technology will likely first be tested on unmanned aircrafts, leading to aircrafts flying for a long time, to help deliver Internet access or medicine to remote villages.”

1.Why is the Wright brothers' airplane mentioned in the text?

A. To show the history of aircrafts.

B. To show the development of wings.

C. To show the need to improve planes.

D. To show the structure of conventional planes.

2.What makes planes fly like birds when they tilt?

A. Their ailerons. B. Wires and pulleys.

C. Changeable wings. D. Mechanical control structures.

3.What is Paragraph 4 mainly about?

A. The shape of the new wings.

B. The purpose of the overlapping strips.

C. The working principle of the new wings.

D. The result of wind?tunnel tests of these wings.

4.What does the underlined word “disassemble” mean in Paragraph 6?

A. Replace. B. Analyze.

C. Put away. D. Take apart.

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Dear David;

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Most people realize that fast food isn't the healthiest or best?tasting cuisine(菜肴). It is, however, expected to be fast.

Many chains like McDonald's have struggled with slower food delivery in recent years, because there are more items on the menu. But the world's largest restaurant chain, which serves 68 million customers daily in 119 countries, is trying to change that.

For several months, McDonald's has been testing what's called the “just?for?you experience”. In 200 U S restaurants (and more than 2，000 across the globe), customers are able to order directly from a self?serve kiosk(售貨亭), after which an employee brings the meal directly to the table.

McDonald's chief executive Steve Easterbrook, speaking at a McDonald's in New York's Tribeca neighbourhood on Thursday, said the company has long expected customers to adapt to its business model of ordering at the counter and then waiting to collect their own food. Now, he said, “We're adapting our business around customers.”

It showed that “test runs at more than 500 restaurants…showed an increase in foot traffic and contributed to a mid?single?digit percentage increase in restaurant sales, lifting the 5 to 6 average check by 1, on average.” Customer satisfaction scores also increased, “because families, in particular, appreciate having their food brought to them.”The company also announced the beginning of a new mobile order?and?pay app, which would allow customers to order and pay for food from their smart phones.

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D. It still needs to be observed.

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A. His family don't like McDonald's.

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C. Self?serve kiosks are a good choice.

D. It's hard for him to spend the delivery time.

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