Question

    While staring out of the window during a flight, not everyone will think carefully about the question why airplanes have rounded windows rather than square ones.

Over the years, aerospace engineering has made huge steps in airplane technology, meaning planes can carry more passengers and go faster. The planes have also changed shape to increase safety—including the windows. As commercial air travel took off in the mid－20th century, airline companies began to fly at higher altitudes to lower their cost—the air density(密度) is lower up there, creating less drag(阻力) for airplanes. However, higher altitudes came with problems, like the fact human beings can’t really survive at 30，000 feet. To make that possible, the cabin was changed to a cylindrical(圆柱体) shape to support the pressure inside. But at first, plane builders left in the standard square windows and this expansion meant disaster. The de__Havilland__Comet came into fashion in the 1950s. With a closed cabin, it was able to go higher and faster than other aircraft.

However, where there’s a corner, there’s a weak spot. Windows, having four corners, have four potential weak spots, making them likely to crash under stress—such as air pressure. By curving the window, the stress that would eventually break the window corner is distributed and the chance of it breaking is reduced. Rounded shapes are also stronger and resist deformation(变形), and can thus survive the extreme differences in pressure between the inside and outside of the aircraft.

Fortunately, designers figured out the lack of design pretty quick. Now we have nice, rounded airplane windows that can resist the pressure of traveling altitude. It gives being able to gaze out of your window to the world from 35，000 feet a whole new outlook, doesn’t it?

1.Why did airlines aim to fly at higher altitudes?

A. To save money for less drag.

B. To help the plane to take off.

C. To increase safety of the plane.

D. To carry more passengers and go faster.

2.What does the underlined words “de Havilland Comet” in Paragraph 2 refer to?

A. An aircraft. B. A band. C. A planet. D. A design.

3.Which is the advantage of the rounded window?

A. It increases the air pressure.

B. It weakens the strength of air pressure.

C. It reduces the possibility of breaking up.

D. It helps to survive the extreme weather.

4.Where does this text come from?

A. A newspaper on safe driving. B. A science book on flying.

C. A website on survival skills. D. A magazine on fashion design.

Answer

1.A

2.A

3.C

4.B

【解析】

本文是一篇说明文。文章主要介绍了飞机舷窗由方变圆的原由。

1.细节理解题。根据第二段第三句...airline companies began to fly at higher altitudes to lower their cost—the air density (密度) is lower up there, creating less drag (阻力)for airplanes.可知，航空公司开始在更高的海拔飞行，以降低成本——那里的空气密度更低，对飞机的阻力更小。故选A。

2.推理判断题。下划线并非词义猜测，而是根据第二段最后一句With a closed cabin, it was able to go higher and faster than other aircraft. 中的 it和other aircraft 推测此词所指为一款飞机。故选A。

3.细节理解题。根据第三段第三句By curving the window, the stress that would eventually break the window corner is distributed and the chance of it breaking is reduced.可知，通过弯曲窗户，最终打破窗户角落的压力被分散，打破的机会减少。故选C。

4.推理判断题。本文介绍了社会发展过程中应安全和经济的需求，飞机形状和其舷窗形状的变化，故可以推断出，改文章选自于与飞行有关的书籍。故选B。