2008年12月英语四级快速阅读预测试卷_大学英语阅读

2008年12月英语四级快速阅读预测试卷

　　Airplane Construction

　　Early airplanes were made of wood frames covered by fabric and held in shape by wire. After World War I, airplane designers started to use lightweight metals like aluminum, titanium, and magnesium alloys. A thin skin of metal was riveted into place over metal ribs. Strong epoxy glues are now used for some joints, instead of rivets. As planes grew in size, they became heavier. More powerful engines were developed in order to fly the heavier planes.

　　The use of metals brings with it a problem called metal fatigue. Stress and vibration in flight can cause metal parts eventually to break up. Airplanes must be constantly checked for signs of this trouble. Defective parts must be renewed by aircraft maintenance people.

　　Designers test scale models in wind tunnels before the full sized planes are built. Reactions of the models to high speed air streams give good indications how full sized planes will react in flight. This approach helps save a lot of money. It also helps to make airplanes safe.

　　Airport

　　An airport is a place where airplanes arrive and depart. Passengers leave and arrive on the airplanes and cargo is loaded and unloaded. Large, jet powered airplanes require long runways for takeoffs and landings. Big terminal buildings are necessary to handle thousands of passengers and their baggage. Very large airports usually serve several large cities and cover thousands of acres. Hundreds of planes arrive and depart daily. All this traffic must be carefully controlled to avoid delays and accidents. This is done from a control tower. The tower stands high above the ground. Air traffic controllers, inside the tower, must be able to guide airplanes through their takeoffs and landings.