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  3. The opinion of many engineers is that the architects that designed the New York World Trade Center Twin Towers did a good job in

The opinion of many engineers is that the architects that designed the New York World Trade Center Twin Towers did a good job in

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问题     The opinion of many engineers is that the architects that designed the New York World Trade Center Twin Towers did a good job in designing the buildings. The buildings were safe from the hazards envisioned at the time. Indeed, they were designed to withstand the force of aircraft that might crash into them. They were not, however, designed to withstand the effects of the very high temperatures generated by the ignition of tons of aviation fuel carried by the aircraft.
    Steel lightly covered with concrete is the main structural component of the towers and steel loses a lot of structural strength when heated to 1,100 degrees Centigrade and beyond, as it was. To shield the steel the towers beams were coated with a few centimeters of concrete. That insulation was to provide structural integrity for at least 1 hour of fire. The towers met that test. The south tower lasted 62 minutes. The north, 103 minutes. Tragedy followed when not all could escape prior to the collapse.
    Most experts agree that the Twin Towers were very well-designed. Many also agree that the people planning the attacks were very knowledgeable and aimed the aircraft at a height that would effect the most damage. The aircraft crash and the resulting fuel fed fires were aimed at about the 90th floor. That was just high enough to insure that the upper floors would weaken with the heat and crack down, dropping into the remaining part of the building.
    The mass of the falling top floors created such a falling load that some experts estimate it exceeded by 5 to 10 times normal bearing loads. The effect was like a giant hammer, each floor contributing more weight to be born by the next floor down.
    Were the Trade Towers well designed? Engineers say yes. But the public believes that architects will never again design a tall building without considering the effects of terrorist attacks of all potential kinds. That not only includes the ability of the structure to withstand attack but the means to allow the buildings occupants to escape in time to survive.
Many engineers after September 11 believe that the Twin Towers were well designed because ______.
选项 A、they were designed by the world-famous architects
B、they could withstand any natural hazards such as earthquake or volcano
C、they had an elegant appearance until they were destroyed
D、they could withstand aircraft crashing into it
答案D
解析 本题是细节题。根据文章第一段第2句中的“The buildings were…at the time．”和第3句中的“Indeed，they were…crash into them．”可以推出：许多工程师认为双子楼设计得很好，主要原因是它们在遭受撞机后没有立刻倒塌。
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