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 increase safety of the plane.

B. To help the plane to take off.

C. To save money for less drag.

D. To carry more passengers and go faster.

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

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

3.Which is the advantage of the rounded window?

A. It reduces the possibility of breaking up.

B. It weakens the strength of air pressure.

C. It increases the air pressure.

D. It helps to survive the extreme weather.

4.Where does this text come from?

A. A newspaper on safe driving. B. A magazine on fashion design.

C. A website on survival skills. D. A science book on flying.

Answer

1.C

2.C

3.A

4.D

【解析】

本文为说明文，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，飞机在更高的空中飞行可以降低其成本，因为高空空气密度更低，飞机的阻力更小，因而降低成本，故选C。

2.推理判断题。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C。

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，机窗变为圆形之后，破碎机窗的力就得到分散了，机窗破裂的可能性就降低了，故选A。

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，故选自于与飞行有关的书籍，故选D。